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/stack.sh b/stack.sh
index bdbb025..1187851 100755
--- a/stack.sh
+++ b/stack.sh
@@ -539,6 +539,7 @@
 source $TOP_DIR/lib/neutron-legacy
 source $TOP_DIR/lib/ldap
 source $TOP_DIR/lib/dstat
+source $TOP_DIR/lib/zookeeper
 
 # Extras Source
 # --------------
@@ -729,6 +730,11 @@
 
 install_rpc_backend
 
+if is_service_enabled zookeeper; then
+    cleanup_zookeeper
+    configure_zookeeper
+    init_zookeeper
+fi
 if is_service_enabled $DATABASE_BACKENDS; then
     install_database
 fi
@@ -968,6 +974,15 @@
 start_dstat
 
 
+# Zookeeper
+# -----
+
+# zookeeper for use with tooz for Distributed Lock Management capabilities etc.,
+if is_service_enabled zookeeper; then
+    start_zookeeper
+fi
+
+
 # Keystone
 # --------