Support HTTP/1.0

[clue]

This project currently focuses on HTTP/1.1, but I'd like to see some support for HTTP/1.0 as well.

There aren't many major differences, but to list a few:

• No chunked transfer-encoding supported (unless specified otherwise)
• Response body may be terminated by closing connection (https://www.w3.org/Protocols/HTTP/1.0/spec.html#BodyLength)
• No persistent connections (Connection header, keep-alive etc.)
• No pipelining

See also e.g. http://www8.org/w8-papers/5c-protocols/key/key.html