Friendlier message when server happens to be down

[Gosha]

When the server is down you get this huge error message in the middle of your merges.

Traceback (most recent call last):
  File "/usr/lib/python-exec/python2.7/gentwoo", line 146, in <module>
    (result, info) = query.send()
  File "/usr/lib/python-exec/python2.7/gentwoo", line 67, in send
    "Accept": "application/json"}))
  File "/usr/lib64/python2.7/urllib2.py", line 154, in urlopen
    return opener.open(url, data, timeout)
  File "/usr/lib64/python2.7/urllib2.py", line 437, in open
    response = meth(req, response)
  File "/usr/lib64/python2.7/urllib2.py", line 550, in http_response
    'http', request, response, code, msg, hdrs)
  File "/usr/lib64/python2.7/urllib2.py", line 475, in error
    return self._call_chain(*args)
  File "/usr/lib64/python2.7/urllib2.py", line 409, in _call_chain
    result = func(*args)
  File "/usr/lib64/python2.7/urllib2.py", line 558, in http_error_default
    raise HTTPError(req.get_full_url(), code, msg, hdrs, fp)
urllib2.HTTPError: HTTP Error 503: Service Unavailable

Would be nice if it either was just smaller, or queued the changes to push them later silently.