Add support for Pyflakes quality violations: eg. diff-quality --violation=pyflakes
Add pyflakes to requirements.txt
Add pyflakes to README

CI skip
Add a new test violation for pyflakes integration test; update other tests
Add two more integration tests for Pyflakes
Merge pull request #1 from hugovk/intergration_test

Add intergration tests for Pyflakes
Merge pull request #84 from hugovk/master

Add support for Pyflakes quality violations