Adding Python 3 Support

Tests are all now passing for python 2 and python 3!  With this PR, the minimum required django version will be 1.5 since that's the first version of django to officially support python 2 and python 3.

Thanks @chhantyal on the early fixes for this!

@tschellenbach, I'll let you do the actual merge on this so you can have a final look over all the changes.  Then once that's done, can we get a new version out to pypi so the python 3 users can start using it?

This fixes #415.

- https://travis-ci.org/tschellenbach/Django-facebook/builds/27909228