Project class: add method to manage locale exception, update Gaia locales

* Move code from Bugzilla to manage exceptions in a single palce
* Clean up some views:
** accesskey: use getRepositoryLocales, no need for Gaia hack (no accesskeys in Gaia)
** checkvariables: use getLocaleInContext
** gaia: remove Serbian hack, all_locales already has the right list of locale per repo
* Update Gaia locales (master, 1.4): en-GB, fa, mr, nb-NO, sw
* Fix markup error in changelog