* Update jquery.i18n - if messageLocationResolver returns false for
a locale, no server hit will be attempted
* Refactor i18n preparation code to a new method
* Use the ULS RL hooks to find out to which locales it is localized,
pass that list to js to avoid hitting server.
* Also avoid directory scanning in each request by putting
the locale list in cache
Fixes Bug 41454
Change-Id: I0c923b35db01b884e2dd55873dd5fb7384434645
