Update the client API to statically track headers and move constructors

The client Request now uses the same system as a server Response to track
the write status of headers, and the API has been updated accordingly.

Additionally, the Request constructors have been moved onto the Request object
instead of being top-level hyper functions, as this better namespaces the
client and Server.

examples/client.rs

@@ -5,6 +5,7 @@ use std::io::stdout;
 use std::io::util::copy;
 
 use hyper::Url;
+use hyper::client::Request;
 
 fn main() {
     let args = os::args();
@@ -25,12 +26,15 @@ fn main() {
     };
 
 
-    let req = match hyper::get(url) {
+    let req = match Request::get(url) {
         Ok(req) => req,
         Err(err) => fail!("Failed to connect: {}", err)
     };
-    let mut res = req.send().unwrap();
-    
+
+    let mut res = req
+        .start().ok().expect("Error writing Headers.")
+        .send().ok().expect("Error sending Request.");
+
     println!("Response: {}", res.status);
     println!("{}", res.headers);
     match copy(&mut res, &mut stdout()) {