Adding device type

Adding device type on port(eg Ethernet Port,TPort,WPort), Link(Ethernet,Optical..) and Switch(Ethernet,Optical)
Updated Serializers.
Fixed javadoc issue for Enums.

ONOS-1428

Change-Id: Id3e3094f1fbf90154fff9a61e3c0ca36be69c281
diff --git a/src/main/java/net/onrc/onos/core/topology/SwitchImpl.java b/src/main/java/net/onrc/onos/core/topology/SwitchImpl.java
index de4194e..e0e02d5 100644
--- a/src/main/java/net/onrc/onos/core/topology/SwitchImpl.java
+++ b/src/main/java/net/onrc/onos/core/topology/SwitchImpl.java
@@ -98,6 +98,17 @@
         return hosts;
     }
 
+    /**
+     * Returns the switch type of this switch.
+     *
+     * @return switch type {@link net.onrc.onos.core.topology.SwitchType} of this switch.
+     */
+    @Override
+    public SwitchType getSwitchType() {
+        return SwitchType.valueOf(getStringAttribute(TopologyElement.ELEMENT_TYPE,
+                SwitchType.ETHERNET_SWITCH.toString()));
+    }
+
     @Override
     public Iterable<Link> getOutgoingLinks() {
         LinkedList<Link> links = new LinkedList<Link>();