AMBARI-6108. zookeeper client check fails when security enabled (aonishuk)

ambari-server/src/main/resources/stacks/HDP/2.0.6/services/ZOOKEEPER/package/templates/zookeeper_client_jaas.conf.j2

@@ -20,4 +20,5 @@ Client {
 com.sun.security.auth.module.Krb5LoginModule required
 useKeyTab=false
 useTicketCache=true;
+principal="{{zk_principal}}";
 };