Fix PEP8: E126 continuation line over-indented

for hanging indent
Fix PEP8: E501 line too long
Fix PEP8: E241 multiple spaces after ','
Fix PEP8: W391 blank line at end of file
Fix PEP8: E127 continuation line over-indented

for visual indent
Fix PEP8: E226 missing whitespace

around arithmetic operator
Fix PEP8: W293 blank line contains whitespace
Fix PEP8: E121 continuation line under-indented

for hanging indent
Shorten long lines
Drop max line length to 80 characters
Reorder import statements
Run PEP8 on Travis-CI
Calculate coverage and submit to coveralls.io
Shorten long lines
Consolidate Queue response validation
Fix Pylint: Attribute defined outside __init__
Remove unused state

Simplify member and parameter names
Make queue length Pythonic
Rename get_submission -> pop
Rename respond -> put