message: Print friendly message when server starts
  This took me way too long to get working because I didn't realize the
  server was being dropped immediately after I created it.
diff: @@ -441,7 +441,11 @@ pub fn start_web_server(sock_addr: Option<&str>) {
  metrics::UPLOADED_FILES_TOTAL.inc_by(0);
  let cratesfyi = CratesfyiHandler::new();
  - Iron::new(cratesfyi).http(sock_addr.unwrap_or("0.0.0.0:3000")).unwrap();
  + let addr = sock_addr.unwrap_or("0.0.0.0:3000");
  + // need to assign this so it's not dropped before the function ends
  + let _server = Iron::new(cratesfyi).http(addr)
  + .unwrap_or_else(|_| panic!("Failed to bind to socket on {}", addr));
  + info!("Running docs.rs web server on http://{}", addr);
  }
  