Handle port unavailable errors

[kdzwinel]

Right now we are optimistically assuming hat 8080 will be available.

[deju]

@kdzwinel It use 8008 default, not 8080. But you can change the port in main.js.

[kdzwinel]

Modifying source code is not exactly a great user experience :) I'm working on a flag support (based on #29) and, later on, ui for all options #34 .