Install Grunt plugin for csslint

Example usage:

 $ cd /mediawiki/extensions/VisualEditor
 # Or:
 $ cd /oojs/ui
 # Then:
 $ /integration/jenkins/bin/wmfgrunt --cwd="$PWD" csslint

Also:
* Sorted dependencies for readabilty.

Bug: 57899
Change-Id: Ic556b191f85db672390d4ae2f04af8ea14a10b6d