Shared PortBindingInfo abstraction for all servers.

Includes `scheme`, `host`, and `port`, and produces a `url` so that could be opened in a web browser.

Also updates the browser code since we can do that now, and adds a build intsruction for Java 1.6.
 
haven't published it for 2.11 but a while back I factored this into its own library of sorts. https://github.com/softprops/opener any interest in using that instead of vendoring in unfiltered? This code is not really specific to unfiltered.