feat(client): replace default dispatcher

examples/client.rs

@@ -32,9 +32,7 @@ fn main() {
 
     let mut core = tokio_core::reactor::Core::new().unwrap();
     let handle = core.handle();
-    let client = Client::configure()
-        .no_proto()
-        .build(&handle);
+    let client = Client::new(&handle);
 
     let work = client.get(url).and_then(|res| {
         println!("Response: {}", res.status());