Bugfix of bug causing security groups from allow_ssh to remain

When running boot-runcommand-delete scenerio and something happend during this
(for example ssh-timeout) vm was not deleted immidetly, and thus security
groupcould not be deleted.
Adding secgroup cleaning to nova cleanup after servers cleanup to ensure
everything is properly deleted.

Change-Id: I84f7cc27f03c8c54fa40b2b115d49038dad21268