django-cas integration

This branch gets django-cas working (as far as I can tell). In order to test it, you'll need to access your computer from your OSU hostname (e.g. mine is http://salvatorez.tss.oregonstate.edu:8888/), which you can get set up in your /etc/hosts file. Once you do that, CAS-dev will accept any requests you send it and you can verify that logging in works.