Merge pull request #98 from changbl/working

Fix RPCManager cls method bug
Fix InceptionPacket: Failure when calling dhcp.__len__
Merge pull request #99 from powerist/packet

Fix InceptionPacket: Failure when calling dhcp.__len__
Fix dhcp handling bug
Merge pull request #100 from powerist/packet

Fix dhcp handling bug
Remove Topology.dpid_to_dpid

Instead, use ip_to_dpid and dpid_ip_to_port to implement
get_fwd_port() and get_neighbors()