Another try to get Travis builds running on JDK 6
Another try to get Travis builds running on JDK 6

also removed JDK 9 for now, which causes incompatibilities in Maven failsafe plugin, to be solved separately
izpack/izpack,akuhtz/izpack,akuhtz/izpack,Murdock01/izpack,Murdock01/izpack,akuhtz/izpack,Helpstone/izpack,akuhtz/izpack,akuhtz/izpack,izpack/izpack,Murdock01/izpack,izpack/izpack,izpack/izpack,Murdock01/izpack,Helpstone/izpack,Helpstone/izpack,akuhtz/izpack,izpack/izpack,Murdock01/izpack,izpack/izpack,akuhtz/izpack,Helpstone/izpack,Helpstone/izpack,izpack/izpack,Murdock01/izpack,Murdock01/izpack,Helpstone/izpack,Helpstone/izpack