CORD-1244 cleanup use of get_tenant/get_service

Change-Id: Ib7e0efc2c084d891c831451db4bdae3dbd3c9814
diff --git a/xos/attic/header.py b/xos/attic/header.py
index 91b13e7..c51df3e 100644
--- a/xos/attic/header.py
+++ b/xos/attic/header.py
@@ -12,6 +12,7 @@
 import traceback
 from xos.exceptions import *
 from xos.config import Config
+from django.contrib.contenttypes.models import ContentType
 
 class ConfigurationError(Exception):
     pass