Clean up DjangoGoApplicationTestCase a bit and fix all the tests.
Move a bunch of tests from DjangoGoApplicationTestCase to VumiGoDjangoTestCase.
Stop using DjangoGoApplicationTestCase in the wrong places.
Rename put_sample_messages_in_conversation() to something more wieldy and reduce the number of messages we test with in places.
Merge branch 'develop-frontend' into feature/issue-466-refactor-app-tests

Conflicts:
	go/apps/bulk_message/tests/test_views.py
	go/apps/surveys/tests/test_views.py
Oops, forgot to add these changes.
Remove now-unnecessary Travis Riak config hack. (@Hodgestar)
Remove debug print.
Clean up conversation setup a bit.
Merge branch 'feature/issue-466-refactor-app-tests' into develop-frontend
Merge branch 'develop' into develop-frontend