[feedback] x-frame-options header removed.

- x-frame-options header removed from iframe serve endpoint.

Author: frknbasaran

plugins/star-rating/frontend/app.js

@@ -2,7 +2,7 @@ var plugin = {};
 (function (plugin) {
 	plugin.init = function(app, countlyDb) {
 		app.get(countlyConfig.path+'/feedback', function (req, res, next) {
-            res.setHeader('X-Frame-Options','ALLOW-FROM *');
+            res.removeHeader('X-Frame-Options');
             res.render('../../../plugins/star-rating/frontend/public/templates/feedback-popup', {});
         });
 	};