Un-harcoding memcached bind address

The patch adds possibility to configure the address
to be bound by memcached server.

Change-Id: Ie808a6e2c96d1b5b6b381ffb689fe0a317eefe23
Related-PROD: PROD-23544
diff --git a/defaults/openstack/init.yml b/defaults/openstack/init.yml
index 334fd43..441e1c1 100644
--- a/defaults/openstack/init.yml
+++ b/defaults/openstack/init.yml
@@ -14,6 +14,7 @@
     openstack_rabbitmq_port: 5672
     openstack_rabbitmq_x509_enabled: False
     # Openstack memcache
+    openstack_memcached_server_bind_address: 0.0.0.0
     openstack_memcache_security_enabled: False
     openstack_memcache_security_strategy: 'ENCRYPT'
     openstack_memcached_proto_tcp_enabled: True