Further improvements for w3c-test.org

I'm trying to get a coherence list of things that still needs to happen:
- redirect http://test.w3.org/ to http://w3c-test.org/
- look for an additional domain?
- add https://w3c-test.org/

We have http://w3c-test.org/ and http://www.w3c-test.org/ at the moment,
so we seem covered for sub domain.

Anything else?

Philippe