Stop ZooKeeper using ZooKeeper script

Change-Id: Idb3a87e441cec6c18cf4f9247ef03cc53fbee480
diff --git a/onos.sh b/onos.sh
index 0a2ea2e..32888c3 100755
--- a/onos.sh
+++ b/onos.sh
@@ -469,7 +469,10 @@
 }
 
 function stop-zk {
-  kill-processes "ZooKeeper" `jps -l | grep org.apache.zookeeper.server | awk '{print $1}'`
+  echo -n "Stopping ZooKeeper ... "
+  load-zk-cfg
+
+  ${ZK_HOME}/bin/zkServer.sh stop
 }
 
 function status-zk {