[BluetoothDevicesModel] Handle DefaultAdapterChanged

Relates NEMO#699
[NearbyDevicesModel] Fix setAdapterProperty()

Relates NEMO#699
[NearbyDevicesModel] Notice existing adapters

Relates NEMO#699
[NearbyDevicesModel] Notice existing devices

Relates NEMO#699
[NearbyDevicesModel] Properly remove devices

Relates NEMO#699
[NearbyDevicesModel] Handle DefaultAdapterChanged

Relates NEMO#699
[ObexFtp] Fix agent registration

Relates NEMO#699
Add 'coverage' make target

Relates NEMO#699
[tests] Initial commit

Relates NEMO#699