Guard, PG, Bourbon, Q

Adding guard to auto-run specs, rewriting specs to use `let` and thus be **a lot** faster. The whole suite runs in 3 seconds now. Also added the ability to edit comments.
Sorry to say but don't think `contenteditable` will not work for us. We need to open up a real form to keep supporting emoticons (plus other functionality that will later on come like mentions). Also I think we should try to use regular rails form_for with remote: true for consistency throughout the app.