Zookeeper for DLM scenarios

In Tokyo, there was a cross project session on distributed
key locking:
https://etherpad.openstack.org/p/mitaka-cross-project-dlm

In support of the discussion there, we'll need support for
a zookeeper service in Devstack and ability to use libraries
like Tooz for DLM functionality.

In this review, we pick up some configuration files from
monasca-api and copy the lib/template to implement the
zookeeper lifecycle. Those services that need zookeeper
need to add "zookeeper" in ENABLED_SERVICES.

Change-Id: Icef26e5cdaa930a581e27d330e47706776a7f98f
diff --git a/stackrc b/stackrc
index 819aa01..19538c0 100644
--- a/stackrc
+++ b/stackrc
@@ -69,7 +69,7 @@
     # Dashboard
     ENABLED_SERVICES+=,horizon
     # Additional services
-    ENABLED_SERVICES+=,rabbit,tempest,mysql,dstat
+    ENABLED_SERVICES+=,rabbit,tempest,mysql,dstat,zookeeper
 fi
 
 # SQLAlchemy supports multiple database drivers for each database server