Switch to FFI-PCAP for Packet Handling

[claudijd]

Processing from the wire or from pcap are really slow using packetfu.

Consider dropping packefu for the flow handling and only use it for parsing packets that we know we're interested in.

Expected performance gain of doing this will be substancial.

Example: 130mb PCAP takes 373.163299 seconds with PacketFu, the same PCAP can be loaded in ffi-pcap in 5 seconds.

This should significantly improve any sort of live BNAT communications on the wire and most importantly will improve handling of raw pcaps for bnat-pcap and for specs.