Prevent data from leaking to global

lib/abstract-class.js

@@ -513,7 +513,7 @@ AbstractClass.prototype.destroy = function (cb) {
  * @param {Function} callback - callback called with (err, instance)
  */
 AbstractClass.prototype.updateAttribute = function updateAttribute(name, value, callback) {
-    data = {};
+    var data = {};
     data[name] = value;
     this.updateAttributes(data, callback);
 };