Add better cleanup / error handling for keyboard and system interrupts

[ChrisTimperley]

Hitting CTRL+C in Darjeeling currently produces a horrific stack trace.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/darjeeling/evaluator.py", line 216, in _evaluate
    test_outcome = self._run_test(container, candidate, test)
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/darjeeling/evaluator.py", line 149, in _run_test
    bz.containers.test(container, test)  # type: BugZooTestOutcome
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/bugzoo/client/container.py", line 240, in test
    with self.__api.post(path) as r:
  File "/usr/lib64/python3.7/contextlib.py", line 112, in __enter__
    return next(self.gen)
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/bugzoo/client/api.py", line 113, in post
    with contextlib.closing(requests.post(url, **kwargs)) as r:
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/requests/api.py", line 116, in post
    return request('post', url, data=data, json=json, **kwargs)
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/requests/api.py", line 60, in request
    return session.request(method=method, url=url, **kwargs)
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/requests/sessions.py", line 533, in request
    resp = self.send(prep, **send_kwargs)
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/requests/sessions.py", line 646, in send
    r = adapter.send(request, **kwargs)
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/requests/adapters.py", line 498, in send
    raise ConnectionError(err, request=request)
requests.exceptions.ConnectionError: ('Connection aborted.', RemoteDisconnected('Remote end closed connection without response'))

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/urllib3/connection.py", line 160, in _new_conn
    (self._dns_host, self.port), self.timeout, **extra_kw)
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/urllib3/util/connection.py", line 80, in create_connection
    raise err
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/urllib3/util/connection.py", line 70, in create_connection
    sock.connect(sa)
ConnectionRefusedError: [Errno 111] Connection refused

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/urllib3/connectionpool.py", line 603, in urlopen
    chunked=chunked)
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/urllib3/connectionpool.py", line 355, in _make_request
    conn.request(method, url, **httplib_request_kw)
  File "/usr/lib64/python3.7/http/client.py", line 1229, in request
    self._send_request(method, url, body, headers, encode_chunked)
  File "/usr/lib64/python3.7/http/client.py", line 1275, in _send_request
    self.endheaders(body, encode_chunked=encode_chunked)
  File "/usr/lib64/python3.7/http/client.py", line 1224, in endheaders
    self._send_output(message_body, encode_chunked=encode_chunked)
  File "/usr/lib64/python3.7/http/client.py", line 1016, in _send_output
    self.send(msg)
  File "/usr/lib64/python3.7/http/client.py", line 956, in send
    self.connect()
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/urllib3/connection.py", line 183, in connect
    conn = self._new_conn()
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/urllib3/connection.py", line 169, in _new_conn
    self, "Failed to establish a new connection: %s" % e)
urllib3.exceptions.NewConnectionError: <urllib3.connection.HTTPConnection object at 0x7f6b405fd780>: Failed to establish a new connection: [Errno 111] Connection refused

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/requests/adapters.py", line 449, in send
    timeout=timeout
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/urllib3/connectionpool.py", line 641, in urlopen
    _stacktrace=sys.exc_info()[2])
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/urllib3/util/retry.py", line 399, in increment
    raise MaxRetryError(_pool, url, error or ResponseError(cause))
urllib3.exceptions.MaxRetryError: HTTPConnectionPool(host='127.0.0.1', port=6060): Max retries exceeded with url: /containers/dcbb3832-8174-4984-b9ce-5b03f4f5e2ba (Caused by NewConnectionError('<urllib3.connection.HTTPConnection object at 0x7f6b405fd780>: Failed to establish a new connection: [Errno 111] Connection refused'))

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/darjeeling/evaluator.py", line 258, in evaluate
    outcome = self._evaluate(candidate)
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/darjeeling/evaluator.py", line 251, in _evaluate
    del bz.containers[container.id]
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/bugzoo/client/container.py", line 59, in __delitem__
    with self.__api.delete('containers/{}'.format(uid)) as r:
  File "/usr/lib64/python3.7/contextlib.py", line 112, in __enter__
    return next(self.gen)
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/bugzoo/client/api.py", line 141, in delete
    with contextlib.closing(requests.delete(url, **kwargs)) as r:
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/requests/api.py", line 158, in delete
    return request('delete', url, **kwargs)
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/requests/api.py", line 60, in request
    return session.request(method=method, url=url, **kwargs)
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/requests/sessions.py", line 533, in request
    resp = self.send(prep, **send_kwargs)
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/requests/sessions.py", line 646, in send
    r = adapter.send(request, **kwargs)
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/requests/adapters.py", line 516, in send
    raise ConnectionError(e, request=request)
requests.exceptions.ConnectionError: HTTPConnectionPool(host='127.0.0.1', port=6060): Max retries exceeded with url: /containers/dcbb3832-8174-4984-b9ce-5b03f4f5e2ba (Caused by NewConnectionError('<urllib3.connection.HTTPConnection object at 0x7f6b405fd780>: Failed to establish a new connection: [Errno 111] Connection refused'))
unexpected error occurred when evaluating candidate [fccc2688]
Traceback (most recent call last):
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/urllib3/connectionpool.py", line 603, in urlopen
    chunked=chunked)
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/urllib3/connectionpool.py", line 387, in _make_request
    six.raise_from(e, None)
  File "<string>", line 2, in raise_from
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/urllib3/connectionpool.py", line 383, in _make_request
    httplib_response = conn.getresponse()
  File "/usr/lib64/python3.7/http/client.py", line 1321, in getresponse
    response.begin()
  File "/usr/lib64/python3.7/http/client.py", line 296, in begin
    version, status, reason = self._read_status()
  File "/usr/lib64/python3.7/http/client.py", line 265, in _read_status
    raise RemoteDisconnected("Remote end closed connection without"
http.client.RemoteDisconnected: Remote end closed connection without response

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/requests/adapters.py", line 449, in send
    timeout=timeout
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/urllib3/connectionpool.py", line 641, in urlopen
    _stacktrace=sys.exc_info()[2])
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/urllib3/util/retry.py", line 368, in increment
    raise six.reraise(type(error), error, _stacktrace)
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/urllib3/packages/six.py", line 685, in reraise
    raise value.with_traceback(tb)
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/urllib3/connectionpool.py", line 603, in urlopen
    chunked=chunked)
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/urllib3/connectionpool.py", line 387, in _make_request
    six.raise_from(e, None)
  File "<string>", line 2, in raise_from
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/urllib3/connectionpool.py", line 383, in _make_request
    httplib_response = conn.getresponse()
  File "/usr/lib64/python3.7/http/client.py", line 1321, in getresponse
    response.begin()
  File "/usr/lib64/python3.7/http/client.py", line 296, in begin
    version, status, reason = self._read_status()
  File "/usr/lib64/python3.7/http/client.py", line 265, in _read_status
    raise RemoteDisconnected("Remote end closed connection without"
urllib3.exceptions.ProtocolError: ('Connection aborted.', RemoteDisconnected('Remote end closed connection without response'))

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/darjeeling/evaluator.py", line 216, in _evaluate
    test_outcome = self._run_test(container, candidate, test)
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/darjeeling/evaluator.py", line 149, in _run_test
    bz.containers.test(container, test)  # type: BugZooTestOutcome
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/bugzoo/client/container.py", line 240, in test
    with self.__api.post(path) as r:
  File "/usr/lib64/python3.7/contextlib.py", line 112, in __enter__
    return next(self.gen)
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/bugzoo/client/api.py", line 113, in post
    with contextlib.closing(requests.post(url, **kwargs)) as r:
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/requests/api.py", line 116, in post
    return request('post', url, data=data, json=json, **kwargs)
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/requests/api.py", line 60, in request
    return session.request(method=method, url=url, **kwargs)
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/requests/sessions.py", line 533, in request
    resp = self.send(prep, **send_kwargs)
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/requests/sessions.py", line 646, in send
    r = adapter.send(request, **kwargs)
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/requests/adapters.py", line 498, in send
    raise ConnectionError(err, request=request)
requests.exceptions.ConnectionError: ('Connection aborted.', RemoteDisconnected('Remote end closed connection without response'))

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/urllib3/connection.py", line 160, in _new_conn
    (self._dns_host, self.port), self.timeout, **extra_kw)
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/urllib3/util/connection.py", line 80, in create_connection
    raise err
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/urllib3/util/connection.py", line 70, in create_connection
    sock.connect(sa)
ConnectionRefusedError: [Errno 111] Connection refused

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/urllib3/connectionpool.py", line 603, in urlopen
    chunked=chunked)
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/urllib3/connectionpool.py", line 355, in _make_request
    conn.request(method, url, **httplib_request_kw)
  File "/usr/lib64/python3.7/http/client.py", line 1229, in request
    self._send_request(method, url, body, headers, encode_chunked)
  File "/usr/lib64/python3.7/http/client.py", line 1275, in _send_request
    self.endheaders(body, encode_chunked=encode_chunked)
  File "/usr/lib64/python3.7/http/client.py", line 1224, in endheaders
    self._send_output(message_body, encode_chunked=encode_chunked)
  File "/usr/lib64/python3.7/http/client.py", line 1016, in _send_output
    self.send(msg)
  File "/usr/lib64/python3.7/http/client.py", line 956, in send
    self.connect()
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/urllib3/connection.py", line 183, in connect
    conn = self._new_conn()
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/urllib3/connection.py", line 169, in _new_conn
    self, "Failed to establish a new connection: %s" % e)
urllib3.exceptions.NewConnectionError: <urllib3.connection.HTTPConnection object at 0x7f6b405fd1d0>: Failed to establish a new connection: [Errno 111] Connection refused

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/requests/adapters.py", line 449, in send
    timeout=timeout
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/urllib3/connectionpool.py", line 641, in urlopen
    _stacktrace=sys.exc_info()[2])
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/urllib3/util/retry.py", line 399, in increment
    raise MaxRetryError(_pool, url, error or ResponseError(cause))
urllib3.exceptions.MaxRetryError: HTTPConnectionPool(host='127.0.0.1', port=6060): Max retries exceeded with url: /containers/4421e02e-8b64-47e5-bbcc-3fe992c2ac5f (Caused by NewConnectionError('<urllib3.connection.HTTPConnection object at 0x7f6b405fd1d0>: Failed to establish a new connection: [Errno 111] Connection refused'))

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/darjeeling/evaluator.py", line 258, in evaluate
    outcome = self._evaluate(candidate)
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/darjeeling/evaluator.py", line 251, in _evaluate
    del bz.containers[container.id]
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/bugzoo/client/container.py", line 59, in __delitem__
    with self.__api.delete('containers/{}'.format(uid)) as r:
  File "/usr/lib64/python3.7/contextlib.py", line 112, in __enter__
    return next(self.gen)
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/bugzoo/client/api.py", line 141, in delete
    with contextlib.closing(requests.delete(url, **kwargs)) as r:
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/requests/api.py", line 158, in delete
    return request('delete', url, **kwargs)
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/requests/api.py", line 60, in request
    return session.request(method=method, url=url, **kwargs)
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/requests/sessions.py", line 533, in request
    resp = self.send(prep, **send_kwargs)
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/requests/sessions.py", line 646, in send
    r = adapter.send(request, **kwargs)
  File "/home/chris/.local/share/virtualenvs/darjeeling-KYygC-ZZ/lib/python3.7/site-packages/requests/adapters.py", line 516, in send
    raise ConnectionError(e, request=request)
requests.exceptions.ConnectionError: HTTPConnectionPool(host='127.0.0.1', port=6060): Max retries exceeded with url: /containers/4421e02e-8b64-47e5-bbcc-3fe992c2ac5f (Caused by NewConnectionError('<urllib3.connection.HTTPConnection object at 0x7f6b405fd1d0>: Failed to establish a new connection: [Errno 111] Connection refused'))