add loading blockHandler.js srcipt into editor html

backstage/templates/editor.html

@@ -12,6 +12,7 @@
         <script type="text/javascript" src="{{url_for('static', filename='config.js')}}"></script>
         <script type="text/javascript" src="{{url_for('static', filename='js/utils.js')}}"></script>
         <script type="text/javascript" src="{{url_for('static', filename='js/blockElements.js')}}"></script>
+        <script type="text/javascript" src="{{url_for('static', filename='js/blockHandler.js')}}"></script>
         <script type="text/javascript" src="{{url_for('static', filename='js/parsers.js')}}"></script>
         <script type="text/javascript" src="{{url_for('static', filename='js/editor.js')}}"></script>
       </div>