Allow setting the port when the WebServer is actual started

[chtheis]

Maybe I do strange things ... :)

I use the WebServer as an embedded server. The server is setup once, i.e., all handlers added and started / stopped by the use. Before actually starting the server the user may change the port the server is listening on. Unfortunately here the port can only be set when the server instance is created, though those settings aren't used until the server is actually started.

I have a patch where the server has a default constructor (no port at all) and a start method with a port parameter. The port must be specified once (at least), either in the constructor or in the start method.

[joewalnes]

Sounds reasonable.