Add ssh check to quantum smoke test.

 * Doing a ping check to verify that a vm is reachable may result
   in false positives if the target ip is routed to a different
   reachable host.  This patch adds an ssh check that will fail
   if the target is not configured an ssh key that was generated
   as part of the test run.

Change-Id: I4112ad9a8854fc113d5fefc7ea03a55da7d0ed1b
Adding a 5s timeout to the default ssh check.

Change-Id: I7b9025ca72bd58bc538fdd405882c39462a05357