ONOS-1864 -- Topology view sending events after view changed

 - it helps if we remove the model listeners when the UI tells us to stop monitoring topology.

Change-Id: I272a664cdddecf584b20e496eebed3275fc9a9aa

@@ -289,6 +289,7 @@ public class TopologyViewMessageHandler extends TopologyViewMessageHandlerBase {
 
         @Override
         public void process(long sid, ObjectNode payload) {
+            removeListeners();
             stopSummaryMonitoring();
             traffic.stopMonitoring();
         }