Add ssh check to quantum smoke test.

 * Doing a ping check to verify that a vm is reachable may result
   in a false positive if the target ip is routed in error to a
   nonetheless pingable host.  This patch adds an ssh check that will
   fail if the target is not configured with the expected (and
   dynamically generated) ssh keypair.
 * Adding the ssh check uncovered a bug in security group creation -
   source group rules were being used that restricted traffic to
   ports associated with the security group.  This is now fixed.
 * Addresses bug 1182343

Change-Id: I4112ad9a8854fc113d5fefc7ea03a55da7d0ed1b
diff --git a/etc/tempest.conf.sample b/etc/tempest.conf.sample
index 3147859..dc26e18 100644
--- a/etc/tempest.conf.sample
+++ b/etc/tempest.conf.sample
@@ -63,6 +63,10 @@
 flavor_ref = 1
 flavor_ref_alt = 2
 
+# User names used to authenticate to an instance for a given image.
+image_ssh_user = root
+image_alt_ssh_user = root
+
 # Number of seconds to wait while looping to check the status of an
 # instance that is building.
 build_interval = 10