Remove IOFSwitch references from ITopologyService interface.

...tcontroller/devicemanager/internal/DeviceManagerImpl.java

.../java/net/floodlightcontroller/forwarding/Forwarding.java

...a/net/floodlightcontroller/topology/ITopologyService.java

...java/net/floodlightcontroller/topology/SwitchCluster.java

.../floodlightcontroller/topology/internal/TopologyImpl.java

...troller/devicemanager/internal/DeviceManagerImplTest.java

...a/net/floodlightcontroller/forwarding/ForwardingTest.java

...odlightcontroller/topology/internal/TopologyImplTest.java