Add Gitter Chat badge
Add Grunt variable for images directory. Access it with `<%config.img.dir%>
version bump to 4.0.2
Forgot to add images var for `grunt clean` task
Merge commit 'da911244d1bb2d5ad2615465a68e2458d4ce41f4'

Conflicts:
	Gruntfile.js
	_grunt-configs/icons.js
	_grunt-configs/utilities.js
	_grunt-configs/watch.js