Update gitignore
Move tests to real django app and add more tests

It was easier to add the boilerplate of a django app than to keep
expanding the MockQuerySet to support all the desired behaviors of a
real queryset. It's also better to test something that matches a real
environment better.
Remove unused optional arg
Merge pull request #20 from steventlamb/topic/use_real_django_app_for_tests

Topic/use real django app for tests