(bug 33658) support for {{GRAMMAR:}} in jqueryMsg

(bug 33658) support for {{GRAMMAR:}} in jqueryMsg

This add GRAMMAR support to the mediawiki.jqueryMsg module:

1. make jqueryMsg understand GRAMMAR(case insensitive)
2. mw.language get convertGrammar, can be overridden per language as in
   php
3. Introduce resourceloader module ResourceLoaderLanguageDataModule
4. Language.php get a method to filter wgGrammerForms for the current
   contentLanguage.
5. Qunit tests
6. This code was originally written in jsgrammar branch of svn and had
   reviewed during the last slush time.

Change-Id: I90dd0b2f0cb30fd30539896c292829adc4fc7364