support running the web server an a random port

[avdv]

Setting the port to 0 in the config, starts the server on a random port.

Alas, it seems there is no way to retrieve the port where the service was eventually bound to, currently.

It would be nice if one could use a shared map, say "webserver.config", to query that information (and more?) from the web-server. That would be especially useful in test cases where you don't want to depend on a static port setting.