CORD-1345: Rename PlCoreBase to XOSBase

Change-Id: Iabd4b25ca2d28d25f11d2a0abf427b182c013cdc
diff --git a/xos/attic/header.py b/xos/attic/header.py
index 55d37fb..9e3b924 100644
--- a/xos/attic/header.py
+++ b/xos/attic/header.py
@@ -1,7 +1,7 @@
 from django.db import models
 from django.db.models import *
 from core.models import Service
-from core.models.plcorebase import StrippedCharField
+from core.models.xosbase import StrippedCharField
 import os
 from django.db import models, transaction
 from django.forms.models import model_to_dict