"[NEW] devel/py-test-xvfb"

It's a pytest plugin to run Xvfb for tests.

Done tests in python 2.7 and 3.6:
1 failed, 14 passed.

The failure as the rest of the plugins that I sent seems to be pytest
related, guessing that is about monkeypatching or changing the
environment in runtime.

Looking for OK and someone to commit to CVS.
Needed for other test suites that require pytest-xvfb.

Thanks.