Cleanup dead code in Bluez SDP discovery backend

The change tweaks the discovery debug output log too.

Change-Id: I4ef3e2e8ebaf0d9e593eee35a669641e3914da01
Reviewed-by: Fabian Bumberger <fbumberger@rim.com>
Reviewed-by: Aaron McCarthy <mccarthy.aaron@gmail.com>
Improve QBluetoothServiceDiscoveryAgent documentation

[ChangeLog][QtBluetooth][QBluetoothServiceDiscoveryAgent] The
QBluetoothServiceDiscoveryAgent class documentation has been improved.

Change-Id: I5472e9ceda45d9bcf0634b5bf2cecf265986bc10
Reviewed-by: Fabian Bumberger <fbumberger@rim.com>
Reviewed-by: Aaron McCarthy <mccarthy.aaron@gmail.com>
Do not clear result lists while the SDP search is ongoing.

Or bad things will happen...

Change-Id: I7df3925ff5d15f3f904f4dd38e24b247ec151fd1
Reviewed-by: Fabian Bumberger <fbumberger@rim.com>
Reviewed-by: Aaron McCarthy <mccarthy.aaron@gmail.com>