yahns 1.10.0 - minor updates

* test_client_expire: favor Process.spawn over fork+exec
* extras/try_gzip_static: require readability on HEAD requests
* proxy_pass: quiet down ECONNRESET and EPIPE, too
* copyright updates
* update various comments
* proxy_http_response: use frozen string literal optimization
* README: add link to NNTP archive endpoint
* use olddoc 1.1.0 for generating NEWS + NEWS.atom.xml
* gemspec fixes for various RubyGems versions
* bytecode golfing to cut a few bytes of memory
* simplify sd_listen_fds emulation
* gemspec: allow compatibility with unicorn 5