Merge pull request #53 from bodepd/master

fix tempest invocation
update vm destruction

Previously, the multi_node vm destroy method did not
ensure that all controller's were destroyed. If you were
to run both a multi_node and multi_node_tempest run on the
same node, it leads to a case were two controllers exist and
there is an ip address conflict.

This commit updates the vm destroy methods need to ensure that they destroy all
multi-node vms.