DO NOT MERGE: USB accessory support library

This provides a mechanism for developing applications to work with
USB accessories in versions of android prior to the introduction
of the android.hardware.UsbManager APIs.

Applications should link against the com.android.future.usb.accessory
library to use this support.

Change-Id: I0b61e20b63eec42c506f0895a0c9a439bdfdf7f5
Signed-off-by: Mike Lockwood <lockwood@android.com>