wait for the vm to be powered off before removing it

Signed-off-by: Dominik Richter <dominik.richter@gmail.com>
check the vm is not yet powered off before trying to power it off

Signed-off-by: Dominik Richter <dominik.richter@gmail.com>
added more versions to travis testing

Signed-off-by: Dominik Richter <dominik.richter@gmail.com>