Pushed Switch Mastership Events into the Topology event channel.
Needed for ONOS-1729
For now those events are not used.

Also, added new TopologyElement attribute type: TYPE_ALL_LAYERS
which applies to the Mastership Events.

NOTE: Currently, those events are intercepted within the
Floodlight Controller.java class. The interception point might be moved
once it becomes clear whether the event origin should be the mastership
election mechanism or the "role change request" accepted by the switch.
In addition, the interception point needs to be moved/ported as appropriate
once we move to the newer 1.3 OpenFlow driver implementation and eventloop.

Change-Id: Iff06ed5aee867c428a8378e31f9d51dbe3e6b978
diff --git a/src/main/java/net/onrc/onos/core/topology/TopologyElement.java b/src/main/java/net/onrc/onos/core/topology/TopologyElement.java
index f70e7f5..bb32958 100644
--- a/src/main/java/net/onrc/onos/core/topology/TopologyElement.java
+++ b/src/main/java/net/onrc/onos/core/topology/TopologyElement.java
@@ -26,13 +26,20 @@
      */
     public static final String TYPE = "type";
     /**
-     * Attribute "type" value representing that the object belongs to Packet layer.
+     * Attribute "type" value representing that the object belongs to Packet
+     * layer.
      */
     public static final String TYPE_PACKET_LAYER = "packet";
     /**
-     * Attribute "type" value representing that the object belongs to Optical layer.
+     * Attribute "type" value representing that the object belongs to Optical
+     * layer.
      */
     public static final String TYPE_OPTICAL_LAYER = "optical";
+    /**
+     * Attribute "type" value representing that the object belongs to all
+     * layers.
+     */
+    public static final String TYPE_ALL_LAYERS = "AllLayers";
 
     public static final String ELEMENT_CONFIG_STATE = "ConfigState";