cargo fmt (#604)

Run rustfmt and setup CI to check for it.

examples/async.rs

@@ -1,16 +1,11 @@
 #![deny(warnings)]
 
-extern crate futures;
-extern crate reqwest;
-extern crate tokio;
-
-use std::mem;
-use std::io::{self, Cursor};
 use futures::{Future, Stream};
 use reqwest::r#async::{Client, Decoder};
+use std::io::{self, Cursor};
+use std::mem;
 
-
-fn fetch() -> impl Future<Item=(), Error=()> {
+fn fetch() -> impl Future<Item = (), Error = ()> {
     Client::new()
         .get("https://hyper.rs")
         .send()
@@ -23,10 +18,9 @@ fn fetch() -> impl Future<Item=(), Error=()> {
         .map_err(|err| println!("request error: {}", err))
         .map(|body| {
             let mut body = Cursor::new(body);
-            let _ = io::copy(&mut body, &mut io::stdout())
-                .map_err(|err| {
-                    println!("stdout error: {}", err);
-                });
+            let _ = io::copy(&mut body, &mut io::stdout()).map_err(|err| {
+                println!("stdout error: {}", err);
+            });
         })
 }