title: create-react-app generates function instead of class in App.js
body: <p>I'm trying to create react app using create-react-app command,
  and it's generating the App.js file as function (es5 syntax without class)
  instead of class (Example in the following code):</p>
  
  <pre><code>import React from 'react';
  import logo from './logo.svg';
  import './App.css';
  
  function App() {
    return (
      &lt;div className="App"&gt;
        &lt;header className="App-header"&gt;
          &lt;img src={logo} className="App-logo" alt="logo" /&gt;
          &lt;p&gt;
            Edit &lt;code&gt;src/App.js&lt;/code&gt; and save to reload.
          &lt;/p&gt;
          &lt;a
            className="App-link"
            href="https://reactjs.org"
            target="_blank"
            rel="noopener noreferrer"
          &gt;
            Learn React
          &lt;/a&gt;
        &lt;/header&gt;
      &lt;/div&gt;
    );
  }
  
  export default App;
  </code></pre>
  
  <p>How can I force create-react-app to generate class instead?</p>