Abstract out NetworkStream

This introduces a new Trait, NetworkStream, which abstracts over
the functionality provided by TcpStream so that it can be easily
mocked and extended in testing and hyper can be used for
other connection sources.

src/lib.rs

@@ -1,7 +1,7 @@
 //! # hyper
-#![feature(macro_rules, phase)]
+#![feature(macro_rules, phase, default_type_params)]
 #![warn(missing_doc)]
-#![deny(warnings)]
+//#![deny(warnings)]
 #![experimental]
 
 extern crate time;
@@ -53,6 +53,7 @@ macro_rules! trace(
 pub mod client;
 pub mod method;
 pub mod header;
+pub mod net;
 pub mod server;
 pub mod status;
 pub mod uri;