Send a new notification for non-HUN notifications

Reusing a previously HUN for a non-incoming call notification
can lead to unexpected behavior with the NotificationManager.

Instead, keep track of what kind of notification we are currently
displaying, so that we can cancel the old HUN and display a new
notification if the need arises.

Also log a little less verbosely when creating notification actions.

Bug: 21926442
Change-Id: Id888b65aeecded6b9ca22f7cf36b265af3d93327