Discourse sent only translation overrides for the current language to the client instead of sending overrides from fallback locales as well. This especially impacted en_GB -> en since most overrides would be done in English instead of English (UK).
This also adds lots of tests for previously untested code.
There's a small caveat: The client currently doesn't handle fallback locales for MessageFormat strings. That is why overrides for those strings always have a higher priority than regular translations. So, as an example, the lookup order for MessageFormat strings in German is:
1. override for de
2. override for en
3. value from de
4. value from en
We used many global functions to handle tests when they should be
imported like other libraries in our application. This also gets us
closer to the way Ember CLI prefers our tests to be laid out.
This is where they should be as far as ember is concerned. Note this is
a huge commit and we should be really careful everything continues to
work properly.
