Flake8 select all

Select all errors, warnings, and flakes.

This makes sure we're taken care of incase more stuff ever gets added
to the default ignores for flake8.

select is implement with a simple prefix match, all the supported prefixes are enumerated here: http://flake8.readthedocs.org/en/latest/warnings.html

I left out `C` and `N` because those are optional plugins we don't use.  Maybe we should, but that sounds like a different pull request.