Add the ability to change the default port

[pazdera]

The VNC app currently supports only the standard VNC port 5900. We should add a switch or some other way of changing the port for people who would like to use a different one.

[pazdera]

This post outlines the idea of what would need changing to accomplish this:

http://world.kano.me/forum/topic/how-to-use-vnc-on-a-different-network