Includes a validation to disable creating initial networks for Neutron

Neutron external and internal networks are created by default
This commit let developers by configuration to decide if those
networks needs to be created. This is needed to test Neutron DVR
in a distributed Multi-node environment

Change-Id: I17d891d072f189925676b4557094cde1c7a71579
Closes-Bug: 1389288
diff --git a/stack.sh b/stack.sh
index ec13338..ed6a4e3 100755
--- a/stack.sh
+++ b/stack.sh
@@ -1275,7 +1275,7 @@
     start_neutron_agents
 fi
 # Once neutron agents are started setup initial network elements
-if is_service_enabled q-svc; then
+if is_service_enabled q-svc && [[ "$NEUTRON_CREATE_INITIAL_NETWORKS" == "True" ]]; then
     echo_summary "Creating initial neutron network elements"
     create_neutron_initial_network
     setup_neutron_debug