Include CORS headers in styleguide dev response

gulpfile.js

@@ -293,6 +293,7 @@ gulp.task(
         server: {
           baseDir: resolvePath(paths().public.root),
         },
+        cors: true,
         snippetOptions: {
           // Ignore all HTML files within the templates folder
           blacklist: ["/index.html", "/", "/?*"],