Add ability to display revisions

js/components/HeadlineGroup.js

@@ -1,8 +1,10 @@
 import React from 'react';
+import classNames from 'classnames';
 
-export default function({ children }) {
+export default function({ children, secondary = false }) {
   return (
-    <div className="headline-group">
+    <div
+      className={classNames('headline-group', {'headline-group--secondary': secondary})}>
       {children}
     </div>
   );