(bug 41994) display labels and descriptions in user languages

This gets the user languages as specified in Babel and then
displays them on the entity page. Will be extended to allow
direct editing and also to select the languages a bit smarter.
Currently set as experimental.

Change-Id: Ie91ca208d32e6a6679b95cc9c2e112ec207c26a0
Merge "(bug 41994) display labels and descriptions in user languages"