make_json doesn't work with local unix domain socket, because it doesn't send the request to /json

[edwintorok]

There is only one URI used to determine what to connect to, and what request to send.
For a unix domain socket, you have a path to the socket, but when sending the HTTP request we should send it to /json, do_it in should take 2 URIs: one for connecting, and another relative one to send the request to.

[lindig]

let do_it uri string =
        let uri = Uri.of_string uri in
        let connection = M.make uri in
        lwt result = M.rpc connection string in
        match result with
                | Ok x -> return x
                | Error e ->
                        Printf.fprintf stderr "Caught: %s\n%!" (exn_to_string e)
                        fail e