Use flake8 to enforce Python style conventions

[wesm]

$ flake8 python/
python/grizzly/encoders.py:6:1: F401 'subprocess' imported but unused
python/grizzly/encoders.py:8:1: F403 'from weld.weldobject import *' used; unable to detect undefined names
python/grizzly/encoders.py:21:1: E302 expected 2 blank lines, found 1
python/grizzly/encoders.py:49:13: E128 continuation line under-indented for visual indent
python/grizzly/encoders.py:138:13: E128 continuation line under-indented for visual indent
python/grizzly/grizzly.py:6:1: F403 'from weld.weldobject import *' used; unable to detect undefined names
python/grizzly/grizzly.py:65:80: E501 line too long (84 > 79 characters)
python/grizzly/grizzly.py:67:80: E501 line too long (84 > 79 characters)
python/grizzly/grizzlyImpl.py:7:1: F403 'from encoders import *' used; unable to detect undefined names
python/grizzly/grizzlyImpl.py:8:1: F403 'from weld.weldobject import *' used; unable to detect undefined names
python/grizzly/grizzlyImpl.py:81:80: E501 line too long (85 > 79 characters)
python/grizzly/grizzlyImpl.py:201:80: E501 line too long (81 > 79 characters)
python/grizzly/grizzlyImpl.py:202:35: E128 continuation line under-indented for visual indent
python/grizzly/grizzlyImpl.py:208:80: E501 line too long (92 > 79 characters)
python/grizzly/grizzlyImpl.py:241:80: E501 line too long (81 > 79 characters)
python/grizzly/grizzlyImpl.py:242:35: E128 continuation line under-indented for visual indent
python/grizzly/grizzlyImpl.py:274:35: E128 continuation line under-indented for visual indent
python/grizzly/grizzlyImpl.py:357:80: E501 line too long (81 > 79 characters)
python/grizzly/grizzlyImpl.py:358:35: E128 continuation line under-indented for visual indent
python/grizzly/grizzlyImpl.py:359:35: E128 continuation line under-indented for visual indent
python/grizzly/grizzlyImpl.py:388:80: E501 line too long (87 > 79 characters)
python/grizzly/lazyOp.py:3:1: F403 'from weld.weldobject import *' used; unable to detect undefined names
python/grizzly/numpyImplWeld.py:8:1: F403 'from encoders import *' used; unable to detect undefined names
python/grizzly/numpyImplWeld.py:9:1: F403 'from weld.weldobject import *' used; unable to detect undefined names
python/grizzly/numpyImplWeld.py:52:80: E501 line too long (81 > 79 characters)
python/grizzly/numpyImplWeld.py:53:35: E128 continuation line under-indented for visual indent
python/grizzly/numpyImplWeld.py:86:80: E501 line too long (85 > 79 characters)
python/grizzly/numpyImplWeld.py:120:80: E501 line too long (96 > 79 characters)
python/grizzly/numpyImplWeld.py:128:80: E501 line too long (85 > 79 characters)
python/grizzly/numpyImplWeld.py:129:35: E128 continuation line under-indented for visual indent
python/grizzly/numpyImplWeld.py:129:80: E501 line too long (89 > 79 characters)
python/grizzly/numpyWeld.py:5:1: F403 'from weld.weldobject import *' used; unable to detect undefined names
python/grizzly/numpyWeld.py:83:80: E501 line too long (86 > 79 characters)
python/grizzly/numpyWeld.py:89:80: E501 line too long (86 > 79 characters)
python/weld/__init__.py:2:1: F401 'bindings' imported but unused
python/weld/__init__.py:3:1: F401 'encoders' imported but unused
python/weld/__init__.py:4:1: F401 'types' imported but unused
python/weld/__init__.py:5:1: F401 'weldobject' imported but unused
python/weld/bindings.py:5:1: F403 'from ctypes import *' used; unable to detect undefined names
python/weld/bindings.py:8:1: F401 'os' imported but unused
python/weld/bindings.py:25:1: E302 expected 2 blank lines, found 1
python/weld/bindings.py:25:30: E701 multiple statements on one line (colon)
python/weld/bindings.py:26:1: E302 expected 2 blank lines, found 0
python/weld/bindings.py:26:28: E701 multiple statements on one line (colon)
python/weld/bindings.py:27:1: E302 expected 2 blank lines, found 0
python/weld/bindings.py:27:29: E701 multiple statements on one line (colon)
python/weld/bindings.py:29:1: E302 expected 2 blank lines, found 1
python/weld/bindings.py:32:80: E501 line too long (82 > 79 characters)
python/weld/bindings.py:41:80: E501 line too long (97 > 79 characters)
python/weld/encoders.py:6:1: F403 'from types import *' used; unable to detect undefined names
python/weld/encoders.py:13:1: E302 expected 2 blank lines, found 1
python/weld/encoders.py:25:1: E302 expected 2 blank lines, found 1
python/weld/encoders.py:57:1: E302 expected 2 blank lines, found 1
python/weld/encoders.py:58:6: E111 indentation is not a multiple of four
python/weld/encoders.py:59:10: E111 indentation is not a multiple of four
python/weld/encoders.py:60:10: E111 indentation is not a multiple of four
python/weld/encoders.py:61:10: E111 indentation is not a multiple of four
python/weld/types.py:8:1: F403 'from ctypes import *' used; unable to detect undefined names
python/weld/types.py:17:1: W293 blank line contains whitespace
python/weld/types.py:34:1: W293 blank line contains whitespace
python/weld/types.py:60:1: W293 blank line contains whitespace
python/weld/types.py:79:1: W293 blank line contains whitespace
python/weld/types.py:123:1: W293 blank line contains whitespace
python/weld/types.py:145:1: W293 blank line contains whitespace
python/weld/types.py:162:1: W293 blank line contains whitespace
python/weld/weldobject.py:8:1: F401 'sys' imported but unused
python/weld/weldobject.py:9:1: F401 'os' imported but unused
python/weld/weldobject.py:10:1: F401 'np' imported but unused
python/weld/weldobject.py:15:1: F403 'from types import *' used; unable to detect undefined names
python/weld/weldobject.py:17:1: E302 expected 2 blank lines, found 1
python/weld/weldobject.py:35:1: E302 expected 2 blank lines, found 1
python/weld/weldobject.py:47:1: E302 expected 2 blank lines, found 1
python/weld/weldobject.py:61:80: E501 line too long (82 > 79 characters)
python/weld/weldobject.py:66:80: E501 line too long (84 > 79 characters)
python/weld/weldobject.py:69:80: E501 line too long (84 > 79 characters)
python/weld/weldobject.py:124:80: E501 line too long (100 > 79 characters)
python/weld/weldobject.py:125:17: E128 continuation line under-indented for visual indent
python/weld/weldobject.py:127:80: E501 line too long (90 > 79 characters)
python/weld/weldobject.py:139:80: E501 line too long (88 > 79 characters)
python/weld/weldobject.py:170:80: E501 line too long (97 > 79 characters)
python/weld/weldobject.py:178:80: E501 line too long (93 > 79 characters)
python/weld/weldobject.py:198:1: W391 blank line at end of file