Migrate Control Panel to Bootstrap

Features:
- [x] Consistent view for Control Panel pages #499 #454 
- [x] No more tables/tabs overlapping #489 
- [x] Sexier, properly coloured buttons (e.g. green for edit, red for remove/reset) with suggestive icons (mainly for add/edit/remove) #467 
- [x] Sidebar active class highlighting. #451 (Games are still not highlighted. Will be after fixing this #452)

... and many more.

I think we should merge this as soon as possible to avoid conflicts when editing templates (while working on something else) and to identify display problems/add-remove unnecessary stuff.