1.0.0: HTTP/1.0 handling

• Fixed handling of HTTP/1.0 requests:
  • Answer with HTTP/1.0 in response status line
  • Close connection unless Connection: keep-alive is sent
  • Do not answer with chunked with persistent connections, see
    https://tools.ietf.org/html/rfc2068#section-19.7.1
    (@thekid)