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/PortImpl.java b/src/main/java/net/onrc/onos/core/topology/PortImpl.java
index 2521a9a..3f4cdfb 100644
--- a/src/main/java/net/onrc/onos/core/topology/PortImpl.java
+++ b/src/main/java/net/onrc/onos/core/topology/PortImpl.java
@@ -152,6 +152,18 @@
         }
     }
 
+    /**
+     * Returns the port type of this port.
+     *
+     * @return {@link net.onrc.onos.core.topology.PortType}
+     */
+    @Override
+    public PortType getPortType() {
+        return PortType.valueOf(getStringAttribute(TopologyElement.ELEMENT_TYPE,
+                PortType.ETHERNET_PORT.toString()));
+    }
+
+
     @Override
     public String getStringAttribute(String attr) {
         return this.topology.getPortEvent(id).getStringAttribute(attr);