default translations and access to Locale

[duanemay]

Added 2 features:

• the ability to have a common default translations file located in app/locales/translations.js
  I use this for product names, and language names that transcend the locale...
  And therefore I don't want to define it in every base language.
• expose Locale so that I can access translations for a certain language from the code. This is useful in the missing-message.js

[jamesarosen]

#256 has some good discussion on the fallback/default locale. I think the approach we want to take is to be able to do i18n.set('defaultLocale', 'es') and have all locales fall back to es/translations.js.

#312 has some good discussion on providing an override locale for one translation. #381 has a prerequisite for the feature. It involves a reserved key name, which is a breaking change, so this can't go out (by default) until 5.0, though we can add a flag to opt-in early.

[toranb]

@duanemay any chance this might still be on your radar (knowing you kicked this off back in the summer of 2016) ?

[toranb]

@jamesarosen did this "breaking change" you mention above land in 5X? Does that unlock anything if someone (like me?) decides to take this back on at some point?

[duanemay]

@toranb I am no longer in a position where we are using ember, so by all means, you can take it on if you wish.

[toranb]

@duanemay sounds like a plan! Care to close this PR? I'll open mine here in a few ;)

[toranb]

#478

^I just threw this PR up to help us land a solution for default locale fallback ;)