Unittest port override using environment variables

[eLvErDe]

Hello,

I have a pull request ready that allow overriding of hardcoded tcp/8000 and tcp/8001 ports used during unittest using an environment variable.
It's very trivial but really helpful to me as it allow running tests while having another app bound on port 8000. It's also very useful for distributions packager so they can setup these environment variables to find dynamically a random available port.

It's a 8 hunks PR, very trivial:
eLvErDe@037d708

Does it makes sense ? Should I go for a PR ?

Regards, Adam.