Make StorybookControls proptypes as non-required

src/client/ui/action_logger.js

@@ -26,7 +26,7 @@ const ActionLogger = ({actionLog}) => (
 );
 
 ActionLogger.propTypes = {
-  actionLog: React.PropTypes.element.isRequired,
+  actionLog: React.PropTypes.string.isRequired,
 };
 
 export default ActionLogger;

src/client/ui/controls.js

@@ -121,9 +121,9 @@ export default class StorybookControls extends React.Component {
 }
 
 StorybookControls.propTypes = {
-  storybook: React.PropTypes.object.isRequired,
-  selectedKind: React.PropTypes.string.isRequired,
-  selectedStory: React.PropTypes.string.isRequired,
-  onKind: React.PropTypes.func.isRequired,
-  onStory: React.PropTypes.func.isRequired,
+  storybook: React.PropTypes.object,
+  selectedKind: React.PropTypes.string,
+  selectedStory: React.PropTypes.string,
+  onKind: React.PropTypes.func,
+  onStory: React.PropTypes.func,
 };