First try at .travis.yml

There are almost certainly problems with the way I'm doing this.

Namely, I'm not sure if I've correctly established the relationships between `django-admin.py test`, `DJANGO_SETTINGS_MODULE` and TravisCI. I'm also not sure if I'm specifying dependencies correctly with `setup.py`.

I also have to write a `setup.py`. 

So basically this is just a first attempt.