Add support to run tests with py.test and coverage. #256
Document py.test usage.
CONTRIBUTING.rst conflict solved.
Update py.test usage examples.
Merge upstream
Resurrect flake8
Rm test_unicode_open, because testing stdlib
Linting and change from dos to unix line endings

To trigger another build
Add `flake8` tox env
Merge branch 'master' into issue_256
Update documentation, fix the flake8 configuration.
Update documentation.
Merge with branch fix_ci of @michaeljoseph
Fix merge conflict
Merge pull request #310 from ramiroluz/issue_256

Document py.test usage instructions. #256