feat(body): rename Entity to Payload

Closes #1464

examples/client.rs

@@ -40,7 +40,7 @@ fn main() {
             println!("Response: {}", res.status());
             println!("Headers: {:#?}", res.headers());
 
-            res.into_body().into_stream().for_each(|chunk| {
+            res.into_body().for_each(|chunk| {
                 io::stdout().write_all(&chunk)
                     .map_err(|e| panic!("example expects stdout is open, error={}", e))
             })

examples/params.rs

@@ -32,7 +32,7 @@ impl Service for ParamExample {
                 Box::new(futures::future::ok(Response::new(INDEX.into())))
             },
             (&Method::POST, "/post") => {
-                Box::new(req.into_parts().1.into_stream().concat2().map(|b| {
+                Box::new(req.into_body().concat2().map(|b| {
                     // Parse the request body. form_urlencoded::parse
                     // always succeeds, but in general parsing may
                     // fail (for example, an invalid post of json), so

examples/web_api.rs

@@ -44,7 +44,7 @@ impl Service for ResponseExamples {
                 let web_res_future = client.request(req);
 
                 Box::new(web_res_future.map(|web_res| {
-                    let body = Body::wrap_stream(web_res.into_body().into_stream().map(|b| {
+                    let body = Body::wrap_stream(web_res.into_body().map(|b| {
                         Chunk::from(format!("before: '{:?}'<br>after: '{:?}'",
                                             std::str::from_utf8(LOWERCASE).unwrap(),
                                             std::str::from_utf8(&b).unwrap()))
@@ -54,7 +54,7 @@ impl Service for ResponseExamples {
             },
             (&Method::POST, "/web_api") => {
                 // A web api to run against. Simple upcasing of the body.
-                let body = Body::wrap_stream(req.into_body().into_stream().map(|chunk| {
+                let body = Body::wrap_stream(req.into_body().map(|chunk| {
                     let upper = chunk.iter().map(|byte| byte.to_ascii_uppercase())
                         .collect::<Vec<u8>>();
                     Chunk::from(upper)