Fix lost packets after connecting

After connecting 4/5 times the MPRIS plugins did not have any players. Apparently the packet with the player list was lost. Logcat showed that an mpris plugin was discarded because no matching plugin was available. Further investigation showed that pluginsByIncomingInterface was empty at that time, probably because the initial fill happens at about the same time, making it racy. Adding 1 second delay to packetReceived made it work properly. Instead of the delay force loading the plugins, which is a bit less hacky. With this patch MPRIS shows players 10/10