Added display of hosts in the topology viewer and fixed a glitch in the host provider.
diff --git a/core/trivial/src/main/java/org/onlab/onos/net/trivial/topology/impl/DefaultTopologyProvider.java b/core/trivial/src/main/java/org/onlab/onos/net/trivial/topology/impl/DefaultTopologyProvider.java
index 6b0e036..b6efba9 100644
--- a/core/trivial/src/main/java/org/onlab/onos/net/trivial/topology/impl/DefaultTopologyProvider.java
+++ b/core/trivial/src/main/java/org/onlab/onos/net/trivial/topology/impl/DefaultTopologyProvider.java
@@ -46,7 +46,8 @@
     private static final int MAX_BATCH_MS = 200;
     private static final int MAX_THREADS = 8;
 
-    // FIXME: Replace with a system-wide timer instance
+    // FIXME: Replace with a system-wide timer instance;
+    // TODO: Convert to use HashedWheelTimer or produce a variant of that; then decide which we want to adopt
     private static final Timer TIMER = new Timer();
 
     private final Logger log = getLogger(getClass());