Django 1.7 support plus testing harness

### What is the problem / feature ?

This project doesn't currently work on django 1.7 because of app loading.  This was not readily apparent due to having no test suite.

### How did it get fixed / implemented ?

- Added local test running through tox
- Added a `travis.yml` to setup continuous integration through travis-ci
- Added a basic smoke test to see that the app can actually load.
- Added testing against django 1.5, 1.6, and 1.7

### How can someone test / see it ?

Travis builds have been enabled on my fork so you can see the status of the tests [here](https://travis-ci.org/pipermerriam/django-cas-ng).  For this to work on the main repository, the travis-ci web hook will have to be enabled.

http://docs.travis-ci.com/user/getting-started/#Step-two%3A-Activate-GitHub-Webhook

*Here is a cute animal picture for your troubles...*

![38523__cute-raccoon-in-pine-tree_p](https://cloud.githubusercontent.com/assets/824194/4925254/9cfc9cd2-6529-11e4-9102-71c83c30df65.jpg)