Fixes #4478 - Added API localization

This PR contains 
- localization setup for apipie
- updated deps on apipie 0.2.0
- strings from apipie-rails to be included to our translation process
- all the API doc strings wrapped into N_()

Related PR in apipie-rails https://github.com/Apipie/apipie-rails/pull/232
apipie-rails actually uses Rails i18n so looks up the *key* and not the string, so these aren't getting translated in the HTML.  I'd suggest changing them to:

<pre>
# TRANSLATORS: Key lookup, English translation is: "Resources"
N_('apipie.resources')
</pre>

(I think that'll work, please test.)