bluetooth: Add handler for RFCOMMListen message

This will allow for ServiceHandlers, the server side of RFCOMM, to be
created.
bluetooth: Add support for registerRFCOMMServiceByUUID

This will create a service handler (in BlueZ terms, a socket listening on
an RFCOMM channel and a SDP record identifying this service), which has a
callback that will be called when a remote device connects to this service.
bluetooth: Add support for notifying that a socket as data available

This adds the SocketHasData message that has as parameters the data
that came from the socket and the socket file descriptor number on
which it came.
packaging: Link with libbluetooth

Now that we are using functions provided by libbluetooth we need to
link against it.