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/files/debs/zookeeper b/files/debs/zookeeper
new file mode 100644
index 0000000..66227f7
--- /dev/null
+++ b/files/debs/zookeeper
@@ -0,0 +1 @@
+zookeeperd
\ No newline at end of file