Bluetooth LE background operation mode (1/2)

Changes to BluetoothAdapter state machine for handling new
states BLE_STATE_ON and intermediate states BLE_TURNING_ON
and BLE_TURNING_OFF. Also includes the actions required
while migrating in and out of these states including
start and stop of GATT services and other profiles.

Change-Id: I08d6ff05c2cefe559d5bb5789a1a488afefbe544