Shamrock should allow to change the testing port or select the next available port

[emmanuelbernard]

Some had shamrock fail because their port were already used 8080.
Either override the port for shamrock tests or use the next available port after 8080.

Did I capture that accurately?

[FroMage]

Normally, what you do is let the server open a port on 0 which gives you a random free port, and then the tests ask the server for its port and use it in the tests: https://docs.oracle.com/javase/7/docs/api/java/net/ServerSocket.html#ServerSocket%28int%29

[Sanne]

Did I capture that accurately?

Missed that I was referring to an existing bug :)

Closing as duplicate of #508