yahns 1.11.0 - more minor updates

There's some minor test case fixes and documentation updates.

For OpenSSL users running the Ruby 2.3.0 preview releases,
we now use `exception: false' for for accept_nonblock to reduce
exceptions.  Non-SSL I/O still uses kgio for now.

6 changes since 1.10.0:
      wbuf: fix typo in bug check for sendfile gem
      test_wbuf: deal with proper zero-copy for Unix sockets
      README: clarify and update copyright year
      doc: document and reference sd_listen_fds(3) behavior
      test_server: fix race condition in hooks test
      openssl_client: use `exception: false' for accept_nonblock