Run Flashlight regardless of the result of port mapping closes #1725

This should do the trick @oxtoacart 
Hmm...good question. I guess if the port mapping actually returned a completely invalid port, the user has UPnP or NAT-PMP enabled, but it's just not working. The only recourse in theory would be for them to set up a static IP and to manually map the port, so theoretically would could have a different error message for that case.