make top-level App component stateless

Author: pheuter

src/common/components/App.js

@@ -1,12 +1,10 @@
 import React from 'react';
 
 
-export default class App extends React.Component {
-  render() {
-    return (
-      <div id="container">
-        {this.props.children}
-      </div>
-    );
-  }
+export default ({children}) => {
+  return (
+    <div id="container">
+      {children}
+    </div>
+  );
 }