FIX & FEAT: support chunked host and add x-forward-for header
Instead of closing the socket when no host is found in the first chunk, return normally and only close the socket as soon as the end of the header has been reached with no host
Moreover, this commit adds a x-forward-for header right after the host field allowing the proxied servers to see the client's real IP
FIX: Echo x-forwarded-for header for testing
If the x-forwarded-for header is available, echo it so the mocha tests can see whether the field was successfully added or not
TEST: Add test that checks for x-forwarded-for header
FIX: add \r before the \n of the X-Forwarded-For header field