Kgio 2.8.0 - kinder, gentler I/O for Ruby + Unix

kgio provides non-blocking I/O methods for Ruby without raising
exceptions on EAGAIN and EINPROGRESS. It is intended for use with the
Unicorn and Rainbows! Rack servers, but may be used by other
applications (that run on Unix-like platforms).


TCP Fast Open in Linux 3.7 and later is now supported
in the client via Kgio::Socket#kgio_fastopen.

This release also adds the kgio_writev and
kgio_trywritev methods, thanks to funny-falcon.