Fix gui-debug template

Author: cdujeu

core/src/plugins/gui.ajax/res/html/gui_debug.html

@@ -15,6 +15,7 @@
     <!--[if IE 7]>
     <script src="plugins/gui.ajax/res/js/vendor/es6/json3.min.js"></script>
     <![endif]-->
+    <script src="plugins/gui.ajax/node_modules/he/he.js"></script>
     <?php
     print($ADDITIONAL_FRAMEWORKS);