Fix issue 2242614: Wired headset not recognized: bogus "state" in ACTION_HEADSET_PLUG broadcast.

The headset state indicated by HeadsetObserver in the broadcast intent ACTION_HEADSET_PLUG was not 0 or 1 as specified in the java doc but contained a bit field indicating the type of headset connected.

Modified HeadsetObserver to broacast a state conforming to java doc.
Added an extra to intent ACTION_HEADSET_PLUG to indicate if headset has a microphone or not.
Removed handling of non standard headset indications from HeadsetObserver.
Removed platform specific devices from output devices defined in AudioSystem.
Modified AudioService to use new ACTION_HEADSET_PLUG intent extra instead of bitfield in state.