Run heat tempest tests if heat is enabled in devstack.

Change-Id: I6a5d1bae99982a8f0201885abd1203e1a8d78dcc
diff --git a/lib/tempest b/lib/tempest
index e59737b..a259ee9 100644
--- a/lib/tempest
+++ b/lib/tempest
@@ -255,6 +255,11 @@
     iniset $TEMPEST_CONF boto http_socket_timeout 30
     iniset $TEMPEST_CONF boto ssh_user ${DEFAULT_INSTANCE_USER:-cirros}
 
+    # orchestration
+    if is_service_enabled heat; then
+        iniset $TEMPEST_CONF orchestration heat_available "True"
+    fi
+
     echo "Created tempest configuration file:"
     cat $TEMPEST_CONF