Print runtime.

src/App.js

@@ -41,6 +41,7 @@ class App extends React.Component {
       y,
       zoomFactor,
     } = this.state;
+    let appContent = <h1>Loading</h1>;
     if (data !== null) {
       let {ratio, timestamp, images, size} = data;
       let width = 512;
@@ -90,6 +91,7 @@ class App extends React.Component {
             <p>{name}</p>
         </div>)
       });
+      appContent = <div><h1>Run @ {new Date(timestamp * 1000).toLocaleString()}</h1>{imgs}</div>;
     }
     return (
       <div>
@@ -109,7 +111,7 @@ class App extends React.Component {
           {zoomFactor}
         </div>
         <div className="App">
-            {imgs}
+          {appContent}
         </div>
       </div>
     );