kgio-monkey 0.4.0 - minor updates and improvements

Do not consider this release (or previous releases) of
kgio-monkey remotely production-ready.  It has not been
reviewed by anybody with any security/crypto background.

* shutdown() is now called before close() after the
  SSL shutdown sequence.  This prevents forked processes
  from holding onto a TCP connection.

* various test fixes for OpenSSL 1.0.0

* documentation updates and fixes (thanks to Iñaki Baz Castillo)

* Errno::ETIMEDOUT exceptions are now raised without a backtrace

* kgio_trysendfile() now uses pread() instead of mmap() when
  emulating sendfile(), this avoids the possibility of SIGBUS
  if an mmap()-ed file is truncated.