Expose l10n data to Javascript

[flack]

Reported by flack on 2 Mar 1912 18:13 UTC ATM, it is very tedious to pass localized strings to javascript, there should be a centralized function for this. F.x. a $.midcom.i18n object that lazily loads lang dbs from a midcom-exec url that returns JSON

Migrated-From: http://trac.openpsa2.org/ticket/146