Large PACKET_IN message from OF10 switch may be truncated.

When a OF13 connection is established, openflowplugin changes miss_send_len to
0xffff by sending a SET_CONFIG message. Alghough the same SET_CONFIG message
should be sent to OF10 switch, openflowplugin does not.

Large packet in PACKET_IN message may be truncated unless miss_send_len value is
not 0xffff. For example, openvswitch initializes miss_send_len to 128 on startup.
So OF10 openvswitch will truncate large packet to 128 bytes when it sends a
PACKET_IN message to the controller.