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/unstack.sh b/unstack.sh
index 30447a7..0cace32 100755
--- a/unstack.sh
+++ b/unstack.sh
@@ -69,6 +69,7 @@
 source $TOP_DIR/lib/neutron-legacy
 source $TOP_DIR/lib/ldap
 source $TOP_DIR/lib/dstat
+source $TOP_DIR/lib/zookeeper
 
 # Extras Source
 # --------------
@@ -172,6 +173,10 @@
     stop_dstat
 fi
 
+if is_service_enabled zookeeper; then
+    stop_zookeeper
+fi
+
 # Clean up the remainder of the screen processes
 SCREEN=$(which screen)
 if [[ -n "$SCREEN" ]]; then