BUG 1084110: Upgrade Stylus & Clean CSS

All ways good to have most recent versions of things both updates inclue bug fixes and the Clean CSS one saves us yet more white space.

Small change to the font-awesome.styl file to remove an unnecissary call that was throwing new Stylus into an infinate loop.
Merge pull request #2849 from stephaniehobson/BUG-1084110-upgrade-stylus

FIX BUG 1084110: Upgrade Stylus & Clean CSS