Reimplemented the ProxyArp app on top of the NeighbourResolutionService.

Also some small API changes to track app ID of handler registrations, and
improved interface matching in NeighbourPacketManager.

Added CLI to view handler registrations.

Change-Id: I8cd0b91a16d9ec60287b65f9d8fc5e3cd87560e8
diff --git a/incubator/api/src/main/java/org/onosproject/incubator/net/neighbour/NeighbourMessageContext.java b/incubator/api/src/main/java/org/onosproject/incubator/net/neighbour/NeighbourMessageContext.java
index f498f17..0c609ae 100644
--- a/incubator/api/src/main/java/org/onosproject/incubator/net/neighbour/NeighbourMessageContext.java
+++ b/incubator/api/src/main/java/org/onosproject/incubator/net/neighbour/NeighbourMessageContext.java
@@ -76,6 +76,16 @@
     MacAddress srcMac();
 
     /**
+     * Gets the destination MAC address of the message.
+     * <p>
+     * Only valid for reply packets, will be null for request packets.
+     * </p>
+     *
+     * @return target MAC address
+     */
+    MacAddress dstMac();
+
+    /**
      * Gets the target IP address of the message.
      *
      * @return target IP address