Bug 1034192, Bug 1034185 - fix app tests

Supersedes https://github.com/mozilla/kuma/pull/2791 with rebase to fix travis ci build.
We do test our own readonly feature here: https://github.com/mozilla/kuma/blob/e35f6bd2d24e2045e0809b278a89fb9a2a28d185/kuma/wiki/tests/test_views.py#L461-L538