UMS [1/6]: LegacyUSB Squashed commit with updates for 4.2

LegacyUSB: add overlay for UMS lun and use existence of lun to enable legacy USB
LegacyUSB: Add support for legacy USB implementations
Option to hide Adb notification icon (framework) - authorship belongs to Rick C

Signed-off-by: Humberto Borba <humberos@gmail.com>
Change-Id: Id14f70f7e21b689c08cadef69f69da711c7dc566

Conflicts:
	services/java/com/android/server/usb/LegacyUsbDeviceManager.java