Touch up examples to ensure consistency

examples/hello.rs

@@ -1,14 +1,34 @@
+//! A small example of a server that accepts TCP connections and writes out
+//! `Hello!` to them, afterwards closing the connection.
+//!
+//! You can test this out by running:
+//!
+//!     cargo run --example hello
+//!
+//! and then in another terminal executing
+//!
+//!     nc -4 localhost 8080
+//!
+//! You should see `Hello!` printed out and then the `nc` program will exit.
+
 extern crate futures;
 extern crate tokio_core;
+extern crate env_logger;
+
+use std::env;
+use std::net::SocketAddr;
 
 use futures::stream::Stream;
 use tokio_core::reactor::Core;
 use tokio_core::net::TcpListener;
 
 fn main() {
+    env_logger::init().unwrap();
+    let addr = env::args().nth(1).unwrap_or("127.0.0.1:8080".to_string());
+    let addr = addr.parse::<SocketAddr>().unwrap();
+
     let mut core = Core::new().unwrap();
-    let address = "127.0.0.1:8080".parse().unwrap();
-    let listener = TcpListener::bind(&address, &core.handle()).unwrap();
+    let listener = TcpListener::bind(&addr, &core.handle()).unwrap();
 
     let addr = listener.local_addr().unwrap();
     println!("Listening for connections on {}", addr);