Empower the service to handle notification acknowledgement and reminder

Add two new actions to the notification service to regroup the camera
change handling:
 * Acknowledge camera changed: The user explicitely acknowledges the
   camera change and what it entails.
 * Remind camera changed later: The user explicitely asks for a
   reminder later.

If the user does not take any explicit action, even if they have tapped
on the notification, the notification will come back after a grace
period (1 day) or on next reboot, whichever comes first.

Change-Id: I12830d06ef49d867d2fa90281352d90366f95750
5 files changed