Add binding for pcap Send

Uses pcap_sendpacket(pcap_handle, buffer, bufLen) to send arbitrary packets on the connected interface.

This is tested and working in Windows 7 with WinPCap 4.1.3 and on Linux with libpcap 1.1.1-10 (Ubuntu precise)

Ok.  I can see the value there.  I dislike encouraging programming by exception but we have to split the difference between getting the error string in time and not getting it at all.  I will follow up with changes later.  Thanks for your patience.