Camera: Cleanup hardware key handling

* Fix power shutter behaviour in camcorder mode
* Disable volume change while in panorama mode, volume buttons should only
handle camera operations while in the camera
* Add camera/power/volume key shutter handling in panorama mode

On devices with a hardware camera key:
* Disable power & volume shutter features
* Volume buttons control the zoom

On devices without a hardware camera key:
* When power shutter is disabled, volume buttons control the shutter (like AOSP)
* When power shutter is enabled, volume buttons control the zoom

Change-Id: I141946d5b6f5aec8b1e9a9f99270d30295596079
Camera: Handle keys only while in app

Thanks to Lars Greiss (SlimRoms)

Change-Id: I63f757d25260fba4683f494f8b4daf178a2b4e13
Merge "Camera: Cleanup hardware key handling" into cm-11.0
Merge "Camera: Handle keys only while in app" into cm-11.0