Python3 support

As per #62 We need to add support for Python3.

This adds support for Py3 and keeps existing py2.6-2.7 support. There is a library that depends on a stale pull request, and it is something I really hope they merge in. And thanks for Neil @drnlm in fixing the last few incompatibilities.
Since we don't pull in South via requirements, we should a "running with Django 1.6" section to the documentation, and mention the need to install South, and also the need to pull this version for python 3 support.