Web Port is now randomized by default. Fixes Issue #301

By default http port is now randomized.
Per @SamPatt , now when the app is running, we automatically open the web browser pointing to the `http://localhost:<random_port_picked>`.

There's an heuristic that makes sure we always pick a free tcp port.

If the user picks a port with `-j` parameter, there was already some logic there to increment the port +1 until a free port is found.