Housekeeping: Simple classes and tests to evaluate phpunit extension
Housekeeping: Let's phpunit decide which phpunit.xml to use ;)

By default a phpunit.xml.dist should be supplied with a project. A user may then overwrite it putting a local phpunit.xml into the tests directory
Fixed: PHPUnit environment does only take one testpath now

Unfortunately more can't be specified on the phpunit commandline
Implemented: Changes based phpunit runs based on filters