DO NOT MERGE: Clean up USB notifications:

Add support for separate USB connected and configuration events

Include both USB connected/disconnected and configuration state
in USB_STATE Intent

Remove redundant USB_CONNECTED and USB_DISCONNECTED Intents
Now we just have the sticky USB_STATE broadcast

Move USB disconnnect rebouncing from Tethering to UsbService

Change-Id: I1dea480f4b0daf14247cf37c5f2060498882c002
Signed-off-by: Mike Lockwood <lockwood@android.com>