Import python3 compatible object.

evennia/objects/models.py

@@ -13,6 +13,7 @@ Attributes are separate objects that store values persistently onto
 the database object. Like everything else, they can be accessed
 transparently through the decorating TypeClass.
 """
+from builtins import object
 
 from django.conf import settings
 from django.db import models

evennia/objects/objects.py

@@ -5,6 +5,7 @@ These are the (default) starting points for all in-game visible
 entities.
 
 """
+from builtins import object
 
 import traceback
 from django.conf import settings