Allows updateAttributes to update only some fields

IT's the same logic as for save(), you can update the whole record or pick the fields you want to update.

lib/dao.js

@@ -201,9 +201,9 @@ module.exports = (function() {
   }
 
 
-  DAO.prototype.updateAttributes = function(updates) {
+  DAO.prototype.updateAttributes = function(updates, fields) {
     this.setAttributes(updates)
-    return this.save()
+    return this.save(fields)
   }
 
   DAO.prototype.setAttributes = function(updates) {