Adding Grunt to compile css when we deploy

Seems to be working ok, my only issue is that in my dev environment, {% debug %} doesn't appear to be available in the template, even though I added it to template_context_processors and set debug = True. 

Anyway, @jamalex is there a good way to test this before going live? It seems to compile fine on my local machine by running `grunt` but I'm not exactly sure how things are set up with ansible.