Update the TopologyMetrics module to listen for all topology-related events:
Devices, Hosts, Links, TopologyEvent

Now the semantics for updating the metrics are:
 * Any topology-related event (DeviceEvent, HostEvent, LinkEvent,
   TopologyEvent) will update the Lost Topology Event Timestamp
 * Only the DeviceEvent, HostEvent and LinkEvent will be counted in
   measuring the event rate; TopologyEvent is excluded, because it
   is generated as a result of some of those events

Also, increased the number of saved events from 10 to 100.

Change-Id: Ie759ee69869cddc617d7ad5b8b75a622e2571620
diff --git a/apps/metrics/topology/src/main/java/org/onlab/onos/metrics/topology/TopologyMetricsService.java b/apps/metrics/topology/src/main/java/org/onlab/onos/metrics/topology/TopologyMetricsService.java
index cc370fa..aeb2e32 100644
--- a/apps/metrics/topology/src/main/java/org/onlab/onos/metrics/topology/TopologyMetricsService.java
+++ b/apps/metrics/topology/src/main/java/org/onlab/onos/metrics/topology/TopologyMetricsService.java
@@ -4,7 +4,7 @@
 
 import com.codahale.metrics.Gauge;
 import com.codahale.metrics.Meter;
-import org.onlab.onos.net.topology.TopologyEvent;
+import org.onlab.onos.event.Event;
 
 /**
  * Service interface exported by TopologyMetrics.
@@ -15,7 +15,7 @@
      *
      * @return the last saved topology events.
      */
-    public List<TopologyEvent> getEvents();
+    public List<Event> getEvents();
 
     /**
      * Gets the Metrics' Gauge for the last topology event timestamp