Merge Hung-Wei's #3 pull request

...dlightcontroller/core/web/serializers/DPIDSerializer.java

...dlightcontroller/core/web/serializers/IPv4Serializer.java

...odlightcontroller/core/web/serializers/MacSerializer.java

...ightcontroller/core/web/serializers/OFPortSerializer.java

...ghtcontroller/core/web/serializers/VlanVidSerializer.java

...va/net/floodlightcontroller/devicemanager/SwitchPort.java

...t/floodlightcontroller/devicemanager/internal/Entity.java

...a/net/floodlightcontroller/topology/TopologyInstance.java