Sets nova auth strategy to keystone

 * Prepares for https://review.openstack.org/#change,4955

Change-Id: I9bacd36d88dc434b1799336e7b2bd8fbf4354bf3
diff --git a/stack.sh b/stack.sh
index 6bf83a6..c7529b8 100755
--- a/stack.sh
+++ b/stack.sh
@@ -1190,6 +1190,7 @@
 rm -f $NOVA_CONF_DIR/$NOVA_CONF
 add_nova_opt "[DEFAULT]"
 add_nova_opt "verbose=True"
+add_nova_opt "auth_strategy=keystone"
 add_nova_opt "allow_resize_to_same_host=True"
 add_nova_opt "scheduler_driver=$SCHEDULER"
 add_nova_opt "dhcpbridge_flagfile=$NOVA_CONF_DIR/$NOVA_CONF"