fix ARP (single onos instance & multiple onos instances)

1. make sure that ARP requests coming from host in a LAN
   are not broadcasted to all other edge ports (other ASes)
2. make sure the ARP requests from BGPd host can be singlecast
   to other ASes
3. add a 'get external network switch ports' function
4. make the arp work for both single onos instance & multiple
   onos instances
5. add a switch ports blacklist. Arp requests are not to be sent
   to those switch ports on this list.

Change-Id: I4ffdd73e2ad202517c54690a86109cfa1fbe400f
diff --git a/src/main/java/net/onrc/onos/apps/forwarding/Forwarding.java b/src/main/java/net/onrc/onos/apps/forwarding/Forwarding.java
index 6758b7a..3e4e1c4 100644
--- a/src/main/java/net/onrc/onos/apps/forwarding/Forwarding.java
+++ b/src/main/java/net/onrc/onos/apps/forwarding/Forwarding.java
@@ -249,7 +249,7 @@
             log.trace("Sending broadcast packet to other ONOS instances");
         }
 
-        packetService.broadcastPacketOutEdge(eth,
+        packetService.broadcastPacketOutInternalEdge(eth,
                 new SwitchPort(sw.getDpid(), inPort.getNumber()));
     }