Active display: Add sunlight mode. [1/2]

Change-Id: I541e74c5a1a7e6ce5028ab00cf998bba1d4fe0f9
Active display: make sure mNotificaiton is set correctly

Change-Id: I4111ca843e340cca4d6dac4b2c2922ce3039e487
Active display: register/unregister recievers and listeners when enabled/disabled

Change-Id: Ic73e63da2c9634bc864ab1a1387eb9145eb0b5b0
Active display: Unify (un)registering callbacks and add proper checks.

Change-Id: Ie4c4660a54d2c60831f7a3bcc66b3a9ca1d035f2
Active display: allow hiding low priority notifications. [1/2]

Change-Id: I4831d6864b509e62b449c25619c59f5d6760ec47