Pass globals to jshint.

JSHINT requires you pass globals as the third argument.  Copied
this pattern from the src/cli.js from jshint itself.
Merge branch 'master' of github.com:bemurphy/jshint.vim into bemurphy-master

* 'master' of github.com:bemurphy/jshint.vim:
  Pass globals to jshint.
Merge branch 'bemurphy-master'

* bemurphy-master:
  Pass globals to jshint.