LegacyUSB: Add support for legacy USB implementations

Rebased for JB 4.2

 This is the 2nd commit message:

LegacyUSB: add overlay for UMS lun and use existence of lun to enable legacy USB

Ported to JB 4.2

 This is the 2nd commit message:

UsbService: LegacyUSB initialize mDeviceManager sooner

 This is the 2nd commit message:

LegacyUsb: fix broadcasts

W/ContextImpl(  424): Calling a method in the system process without a qualified user:

Change-Id: Ibe718dd8e1a3064e5fe289ffd2232522245138ac

Conflicts:
	core/res/res/values/config.xml
	core/res/res/values/symbols.xml