feat(server): add Response.send to write a sized body

Closes #446

examples/hello.rs

@@ -2,15 +2,12 @@
 extern crate hyper;
 extern crate env_logger;
 
-use std::io::Write;
 use hyper::server::{Request, Response};
 
 static PHRASE: &'static [u8] = b"Hello World!";
 
 fn hello(_: Request, res: Response) {
-    let mut res = res.start().unwrap();
+    res.send(PHRASE).unwrap();
-    res.write_all(PHRASE).unwrap();
-    res.end().unwrap();
 }
 
 fn main() {

examples/server.rs

@@ -2,10 +2,9 @@
 extern crate hyper;
 extern crate env_logger;
 
-use std::io::{Write, copy};
+use std::io::copy;
 
 use hyper::{Get, Post};
-use hyper::header::ContentLength;
 use hyper::server::{Server, Request, Response};
 use hyper::uri::RequestUri::AbsolutePath;
 
@@ -22,11 +21,7 @@ fn echo(mut req: Request, mut res: Response) {
     match req.uri {
         AbsolutePath(ref path) => match (&req.method, &path[..]) {
             (&Get, "/") | (&Get, "/echo") => {
-                let out = b"Try POST /echo";
+                try_return!(res.send(b"Try POST /echo"));
-
-                res.headers_mut().set(ContentLength(out.len() as u64));
-                let mut res = try_return!(res.start());
-                try_return!(res.write_all(out));
                 return;
             },
             (&Post, "/echo") => (), // fall through, fighting mutable borrows

src/server/response.rs

@@ -109,8 +109,6 @@ impl<'a, W: Any> Response<'a, W> {
 
         Ok(body_type)
     }
-
-
 }
 
 impl<'a> Response<'a, Fresh> {
@@ -126,6 +124,23 @@ impl<'a> Response<'a, Fresh> {
         }
     }
 
+    /// Writes the body and ends the response.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// # use hyper::server::Response;
+    /// fn handler(res: Response) {
+    ///     res.send(b"Hello World!").unwrap();
+    /// }
+    /// ```
+    pub fn send(mut self, body: &[u8]) -> io::Result<()> {
+        self.headers.set(header::ContentLength(body.len() as u64));
+        let mut stream = try!(self.start());
+        try!(stream.write_all(body));
+        stream.end()
+    }
+
     /// Consume this Response<Fresh>, writing the Headers and Status and creating a Response<Streaming>
     pub fn start(mut self) -> io::Result<Response<'a, Streaming>> {
         let body_type = try!(self.write_head());