better option mergeing

lib/model-factory.js

@@ -6,8 +6,10 @@ module.exports = (function() {
   var ModelFactory = function(name, attributes, options) {
     var self = this
 
-    this.options = options || {}
-    this.options.timestamps = this.options.hasOwnProperty('timestamps') ? this.options.timestamps : true
+    this.options = Utils._.extend({
+      timestamps: true
+    }, options || {})
+
     this.name = name
     this.tableName = this.options.freezeTableName ? name : Utils.pluralize(name)
     this.attributes = Utils.simplifyAttributes(attributes)