Add django-jenkins setup and requirements

Sorry, you're right about `INSTALLED_APPS`. :) But I would still say that if you want to test even your urls or your settings file, you should just use the `--all` option when running the tests with django-jenkins, instead of using `PROJECT_APPS`, which should be IMO used to limit the apps on which tests are run. What do you think?

(I'm nitpicking about this because the module that contains the Django settings and URLs is not a Django app per se)