user list: set pwg_token in POST data to user_list_backend.php

The POST data for the user data table request was empty, which could
cause user data retrieval to error out with HTTP 403 due to missing
the authentication token.

admin/themes/default/template/user_list.tpl

@@ -615,7 +615,13 @@ jQuery(document).on('click', '.close-user-details',  function(e) {
     processing: true,
     serverSide: true,
 		serverMethod: "POST",
-    ajaxSource: "admin/user_list_backend.php",
+    "ajax": {
+        "url" : "admin/user_list_backend.php",
+         "type" : "POST",
+         "data" : {
+            "pwg_token" : pwg_token
+         }
+    },
 		pagingType: "simple",
     language: {
       processing: "{/literal}{'Loading...'|translate|escape:'javascript'}{literal}",