Should pass timeouts to lua-http functions

You should pass timeouts to calls such as `:get_headers()` to prevent clients causing resource exhaustion.

Same for `:write` functions: you don't want to waste resources forever if the client never acks the data.

Btw, on failure you should always try to call `stream:shutdown()` which allows for immediate resource freeing (and in some cases stuff like connection pooling/reuse)