Cleaned up some of the host-related abstractions and filled in more of the host manager implementation.
diff --git a/core/api/src/main/java/org/onlab/onos/net/host/HostEvent.java b/core/api/src/main/java/org/onlab/onos/net/host/HostEvent.java
index b06e8b8..2adfb09 100644
--- a/core/api/src/main/java/org/onlab/onos/net/host/HostEvent.java
+++ b/core/api/src/main/java/org/onlab/onos/net/host/HostEvent.java
@@ -23,6 +23,11 @@
         HOST_REMOVED,
 
         /**
+         * Signifies that host data changed, e.g. IP address
+         */
+        HOST_UPDATED,
+
+        /**
          * Signifies that a host location has changed.
          */
         HOST_MOVED