Make a bit of cleanup with language overrides, so the tests work with various project settings.
Reloading mt_settings in TestAutodiscover._post_teardown is a workaround for FALLBACK_LANGUAGES being changed by these tests due to some interplay of reload_override_setting and the custom TestCase-wide setting override.
Disable timezone support for tests, as the date / time fields' tests use naive datatime objects and fail if it's enabled.
Be prepared to test with various storages or just with the usual FileSystemStorage, but with an overridden location (e.g. when the storage is created in another apps test before MEDIA_ROOT defined for tests gets set).
It would be nice to also find a way to ensure files are cleaned up with non-file-system storages in case test_translated_models_instance fails in the middle.
Merge pull request #153 from wrwrwr/feature/testing-with-app-settings

Fix testing with other apps