On RDP port conflict between system daemon and user daemon, system daemon has more priority
This fixes the 6th item at #180.
This is on top of !222 (merged) because uses the new prompt.
The system daemon has more priority to listen to its port than the user daemon.
On a port conflict, the RDP server of daemon user is restarted and listens to the next available port. When the RDP server is started again, it shows a prompt to inform about the port change.