v1.3.4 Reset DBUS connection on DBUS error

Version 1.3.4 contains one minor enhancement: if the DBUS connection fails, vdu_controls will drop the existing connection and when the next message needs to be sent, it will try to initialise a new one. This should recover from desktop crash/restarts, such as when plasma falls over and is restarted by kstart5 plasmashell

Prior to v1.3.4, vdu_controls just kept trying the existing connection, which would continue to fail and cause a popup dialog to show for each failure.