Fix tests to work with Django 1.6+

Use django-discover-runner to run tests in the case of Django version <
1.6 . Still a little hackish, but viable way to get the tests run for
now.

Update .travis yml to install new requirements before a test run,
update makefile to run tests using discover runner and explicitly use
the settings we have setup in the test project
Merge pull request #28 from mgrouchy/fix-tests-1.6

Fix tests to work with Django 1.6+