added help and made it possible to run two different testsuites on different instances if specified. We could easily add the possibility to force the creation of a new instance for a specific test run but will ignore for now. We could also make it easily possible to run tests on different instances depending on the checked out version but will add once needed. Ideally we could run different testsuites on the same instances at the same time (setup multiple piwiks on one instances or use unique databases during test run)