Add Simplized Chinese.

Just modified the .json in language folder and some .tpl in the
templates folder(except the admin folder). Noted there are a lot of
front-end related code in the .js files, I’ll move on to them.
Merge branch 'master' of github.com:TheRealDrZ/NodeBB into TheRealDrZ-master

Conflicts:
	public/templates/composer.tpl