Add cookie-rs and use cookie::Cookie in Cookie header.

src/lib.rs

@@ -136,6 +136,7 @@ extern crate "unsafe-any" as uany;
 extern crate "move-acceptor" as macceptor;
 extern crate intertwine;
 extern crate typeable;
+extern crate cookie;
 
 pub use std::io::net::ip::{SocketAddr, IpAddr, Ipv4Addr, Ipv6Addr, Port};
 pub use mimewrapper::mime;