Tcp fastopen

For reference: https://portal.sinodun.com/wiki/display/TDNS/TCP+Fast+Open

Tested on IPv4.  No IPv6 client support yet it seems - but IPv6 server support is in the 3.16 Linux kernel (Ubuntu 14.10):
http://kernelnewbies.org/Linux_3.16#head-93fbb9abc6149e9c3055322f27cdc3a8fcc198e6