Refactor QBluetoothDiscoveryModel

- Add the option to discover devices
- Clear the model when a new discovery is started. In the previous implementation the model was only cleared if new data was available.
This can lead to some funny results.
- Change some property types to enums
- Enhance the qmlscanner example

Change-Id: I94f33e3eabd7440b5c0c6c83f3e8158009bd2dbd
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>
BlackBerry: Add some platform documentation

Change-Id: If2a8d289578f3bc7622cedd9faf35893880a2157
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>
Lower the verbosity of bluetooth

Remove some qDebug statements and change qDebugs to qWarning in case of an error.

Task-number: QTBUG-32253

Change-Id: Ia647d3f485cae56cc9f9c6725400f5b4617b7bf7
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>
Add remote address property to QBluetoothDiscoveryModel

Change-Id: I979eaa15d62606206c4c175dcdcaf9d1691f4117
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>