marked sack library as deprecated

lib/scripts/tw-sack.js

@@ -66,6 +66,8 @@ function sack(file){
   };
 
   this.runAJAX = function(urlstring){
+    DEPRECATED('Please use jQuery.post() or any other of jQuery\'s AJAX methods.');
+
     this.responseStatus = new Array(2);
     if(this.failed && this.AjaxFailedAlert){
       alert(this.AjaxFailedAlert);