Handle secondary actions on notifications either specified as a single object,
or as a list of objects. Under the hood, the initialize method converts a single
object to a list containing a single object.
Models are extraneous for something as temporary as a notifaction -- this change
moves all the configuration into the views, and removes the models entirely.
Also, a SystemFeedback model no longer has a `type`, it has an `intent`. This is
because SystemFeedback views have `type`, as well, and this prevents a naming
collision.
It appears that one notification stealing focus from another causes some weirdness:
both clicking on a button on one view triggers the event on both views (the original
and the new view that stole the div). As long as the first view does *not* define
any click events, everything is fine -- this is the case for the saving notification.
I'll worry about the reason for this later; it has something to do with views
listening to models even after they no longer should be.
