Client should validate request URI. (#181)

This patch adds checks for the request URI and rejects invalid URIs. In
the case of forwarding an HTTP 1.1 request with a path, an "http" pseudo
header is added to satisfy the HTTP/2.0 spec.

Closes #179

src/proto/peer.rs

@@ -8,9 +8,6 @@ use std::fmt;
 
 /// Either a Client or a Server
 pub trait Peer {
-    /// Message type sent into the transport
-    type Send;
-
     /// Message type polled from the transport
     type Poll: fmt::Debug;
 
@@ -18,8 +15,6 @@ pub trait Peer {
 
     fn is_server() -> bool;
 
-    fn convert_send_message(id: StreamId, headers: Self::Send, end_of_stream: bool) -> Headers;
-
     fn convert_poll_message(headers: Headers) -> Result<Self::Poll, RecvError>;
 
     fn is_local_init(id: StreamId) -> bool {