Add generate-config option to kolla-ansible

In order for the ansible configuration to be consumable,
we need to be able to generate it without deploying anything.

Change-Id: I2bbdd74d62d00f509a4fa5e4100906ed658d3974
Implements: blueprint generate-config

tools/kolla-ansible

@@ -47,6 +47,7 @@ Commands:
     reconfigure         Reconfigure OpenStack service
     certificates        Generate self-signed certificate for TLS *For Development Only*
     upgrade             Upgrades existing OpenStack Environment
+    genconfig           Generate configuration files for enabled OpenStack services
 EOF
 }
 
@@ -161,6 +162,10 @@ case "$1" in
         ACTION="Generate TLS Certificates"
         PLAYBOOK="${BASEDIR}/ansible/certificates.yml"
         ;;
+(genconfig)
+        ACTION="Generate configuration files for enabled OpenStack services"
+        EXTRA_OPTS="$EXTRA_OPTS -e action=config"
+        ;;
 (*)     usage
         exit 0
         ;;