Merge: Implemented a htcpcp server

An attempt at: https://github.com/nitlang/nit/issues/1808, a fun little example.

As a first step I haven't implemented additions, and gave as best implementation of the protocol as I could interpret it.

It's mostly based on the `file_server.nit` file. If you want to test it locally a good way is to use `curl -X <METHOD> localhost:8080`

@xymus @Bl4ckb0ne @R4PaSs

Pull-Request: #1915
Reviewed-by: Lucas Bajolet <r4pass@hotmail.com>
Reviewed-by: Alexis Laferrière <alexis.laf@xymus.net>
Reviewed-by: Jean Privat <jean@pryen.org>