Overlay: Add ambient mode for hammerhead

Change-Id: I9a879a7741dbaf7a9a4519fb23ad7be702ba9de0
Built in CodeBlue

Change-Id: I08b37ec9abb90a603e85cf8ed07b905a9411f4c4
hammerhead: disable DOZE feature by default

user can enable it if they want it

Change-Id: Ia2a32f8827b21d567405dc86e28b88c71e074294
hammerhead: reenable notification and battery light overlays

Change-Id: I2f52ef61042f6d240cc798d45226e257e17401b9