title: Render async component in React Router v4
body: <p>I want to render a component based on the payload it receives from an api like below</p>
  
  <pre><code>&lt;Route path="/foo/bar" render={() =&gt; {
    return (get('/some/api').then((res) =&gt; {
      return &lt;Baz data={res.data} /&gt;
            }).catch((err) =&gt; console.log))
          }} /&gt;
  </code></pre>
  
  <p>But I'm getting the error:</p>
  
  <pre><code>Objects are not valid as a React child (found: [object Promise]). If you 
  meant to render a collection of children, use an array instead. 
  </code></pre>
  
  <p>even when I do wrap <code>Baz</code> in <code>[]</code></p>