Should close#37. There are persistent and passive notifications.
Persistent ones:
* are stored on `ghost.notifications`.
* have an api made to add / remove them with client side ajax logic (probably not the most elegant, but works)
* uses a modified `flashes.hbs` template
* will only disappear if user closes the bar
* stack
Passive
* added with backbone view / collection combo
* stack
* disappears on navigation and when user closes it
