l.s.u.withxvfb : module documentation

Run a command with a default Xvfb environment

If the command is not found it is searched for in the same directory as this script. This lets you do bin/with-xvfb iharness for example.

Follows sinzui's advice to the launchpad-dev list:

https://lists.launchpad.net/launchpad-dev/msg07879.html