Moved Request/Response related code into different file

Brad, I'm trying to make sense of this code and possibly contribute. I feel it is easier to digest if it is split into smaller chunks. I've noticed the net/http server.go package is currently 2k lines.

This is just a suggestion/idea. What are your thoughts? I would personally go even further and add even more files, splitting the `server` struct's method into different files - not sure what your conventions are on this. I haven't gone too far because I've wanted to first hear your view on this.