Create default flavors in nova

This makes devstack create default flavors in nova, like cinder, now
that nova no longer hard-codes them into its database.

The flavors created here match the legacy default flavors that nova
kept for so long, and also creates a new devstack-namespaces set of
flavors which are likely more useful for people.

Change-Id: Ic275887e97221d9ce5ce6f12cdcfb5ac94e300b0
diff --git a/stack.sh b/stack.sh
index 793b7dc..6e1fe37 100755
--- a/stack.sh
+++ b/stack.sh
@@ -1251,6 +1251,7 @@
 if is_service_enabled nova; then
     echo_summary "Starting Nova"
     start_nova
+    create_flavors
 fi
 if is_service_enabled cinder; then
     echo_summary "Starting Cinder"