Fix some BTLE service discovery issues

1.) In Bluez avoid incomplete and/or premature finish of service
discovery process.

2.) Add Testcode for
QBluetoothServiceInfo::serviceDiscovered(QLowEnergyServiceInfo) to
bttestui application

Change-Id: I037a6303862dcf2e29aef4b761731b13c85b29aa
Reviewed-by: Nedim Hadzic <nedimhadzija@gmail.com>
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>