Adding X-Requested-With header

lib/adapters/xhr.js

@@ -25,6 +25,9 @@ module.exports = function xhrAdapter(resolve, reject, config) {
     config.headers || {}
   );
 
+  // Indicate that request is being made with XHR
+  requestHeaders['X-Requested-With'] = 'XMLHttpRequest';
+
   if (utils.isFormData(data)) {
     delete requestHeaders['Content-Type']; // Let the browser set it
   }