PEP8ify, pyflakes, autodoc

Now depends on celery >= 2.4.2

Updates Changelog

pyflakes

Bumps version to 2.3.3 and updates Changelog

Bumps version to 2.3.2 and updates Changelog

PEP8ify + pyflakes

Bumps version to 2.2.7 and updates changelog

Updates Changelog

Now depends on Celery>=2.2.4