Add access prohibition for external links

src/widgets/ExternalLink.tsx

@@ -2,7 +2,7 @@ import * as React from 'react';
 import { pure } from 'recompose';
 
 export const ExternalLink = pure((props: any) => (
-  <a target="_blank" {...props} />
+  <a target="_blank" rel="noopener" {...props} />
 ));
 
 export default ExternalLink;