only allow apps to temporarily power on Bluetooth
only allow apps to temporarily power on Bluetooth

also disallow powering Bluetooth off while something else is still using it

Change-Id: Icb8f5863e618d628dd40e2c2e169328c239eb81f
Reviewed-by: Alex <3f9b327efd0f2b2e684d51660e829d1496ae5581@nokia.com>

kobolabs/qtconnectivity,kobolabs/qtconnectivity,kobolabs/qtconnectivity