Merge pull request #53 from caglar10ur/patch-3

Update sync_controller_slices.py
diff --git a/xos/openstack_observer/steps/sync_controller_slices.py b/xos/openstack_observer/steps/sync_controller_slices.py
index df44fa5..619a6ed 100644
--- a/xos/openstack_observer/steps/sync_controller_slices.py
+++ b/xos/openstack_observer/steps/sync_controller_slices.py
@@ -5,6 +5,7 @@
 from django.db.models import F, Q
 from xos.config import Config
 from observer.openstacksyncstep import OpenStackSyncStep
+from core.models import User
 from core.models.slice import Slice, ControllerSlice
 from core.models.controlleruser import ControllerUser
 from util.logger import Logger, logging, logger