Rollback premature PR

Apologies - prematurely created PR for py3 without having pushed all local changes. Please find attached a PR to rollback the last changes. Will post a full PR with the whole py3 support in the next couple of days - do apologise!

What is the oldest Python you wish to support with django-colorful - as this will influence the tweaks for py3/py2.x support we need to add.