Pairing Dialogs notifications (in the window shade) were not visible in full
screen apps e.g. gallery. Showing Pairing Dialog in the foreground:
1) if the remote device was picked in the device picker in the last minute or
2) if the device was in discoverable mode in the last minute.
Add incoming pairing dialog
Add DisplayPasskey handling of pairing keyboards with 2.1 devices.
Modify code path to show errors when bonding request fails.
Misc fixes like string changes.
Split BluetoothDevice into BluetoothDevice and BluetoothAdapter.
BluetoothAdapter: Represents the local BT adapter. Operations on the local
adapter (start a scan, etc).
BluetoothDevice: Represents a remote BT device. Operations on remote devices
(pair, connect, etc).
