Fixed update_at bug

@@ -19,7 +19,7 @@ exports = module.exports = function() {
 
       var that = this
 
-      that.updated_at = (!that.created_at) ? Date.now() : that._id.getTimestamp()
+      that.updated_at = _.isUndefined(that.created_at) ? that._id.getTimestamp() : new Date();
 
       if (!that.created_at)
         that.created_at = that._id.getTimestamp()
@@ -37,7 +37,7 @@ exports = module.exports = function() {
       getters: true
     })
 
-    Schema.plugin(jsonSelect, '-_id -__v')
+    Schema.plugin(jsonSelect, '-_id')
 
     return Schema