Added favouriting

Added ability to allow users to favourite wittl items. When favourited
they are saved back and on reload appear favourited. Modified
handlebars template and view.html.

Cleaned formatting in modal.js and imported jQuery cookie.js.
Added ability to unfavourite items

Refactored add_favourite so that it can now remove items in favourites.
autoformatted
Merge branch 'favourites'

Conflicts:
	wittl/api.py