refactor zookeeper into a slightly more generic dlm module

This attempts to make the zookeeper installation a bit more modular
(assuming that other folks will want to add other dlms as plugins),
and addresses the service start issues with zookeeper under
ubuntu/upstart.

Zookeeper is not going to be installed by default. Services need to
ask for it with use_dlm.

Change-Id: I33525e2b83a4497a57ec95f62880e0308c88b34f
diff --git a/stack.sh b/stack.sh
index 68b932e..3cc2158 100755
--- a/stack.sh
+++ b/stack.sh
@@ -539,7 +539,7 @@
 source $TOP_DIR/lib/neutron-legacy
 source $TOP_DIR/lib/ldap
 source $TOP_DIR/lib/dstat
-source $TOP_DIR/lib/zookeeper
+source $TOP_DIR/lib/dlm
 
 # Extras Source
 # --------------
@@ -724,11 +724,10 @@
 
 install_rpc_backend
 
-if is_service_enabled zookeeper; then
-    cleanup_zookeeper
-    configure_zookeeper
-    init_zookeeper
-fi
+# NOTE(sdague): dlm install is conditional on one being enabled by configuration
+install_dlm
+configure_dlm
+
 if is_service_enabled $DATABASE_BACKENDS; then
     install_database
 fi
@@ -968,15 +967,6 @@
 start_dstat
 
 
-# Zookeeper
-# -----
-
-# zookeeper for use with tooz for Distributed Lock Management capabilities etc.,
-if is_service_enabled zookeeper; then
-    start_zookeeper
-fi
-
-
 # Keystone
 # --------