Fixed default status parser to use user model from the model factory. This...

Fixed default status parser to use user model from the model factory. This enables use of one's own user models.

tweepy/models.py

@@ -47,7 +47,8 @@ class Status(Model):
         status = cls(api)
         for k, v in json.items():
             if k == 'user':
-                user = User.parse(api, v)
+                user_model = getattr(api.parser.model_factory, 'user')
+                user = user_model.parse(api, v)
                 setattr(status, 'author', user)
                 setattr(status, 'user', user)  # DEPRECIATED
             elif k == 'created_at':