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

Rebased for ICS 4.0.3

Option to hide Adb notification icon (framework) - authorship belongs to Rick C

Change-Id: Id14f70f7e21b689c08cadef69f69da711c7dc566