SEBA-664 Allow ONU to be manually disabled

Change-Id: Ide9707cc965b4c939cf50d13e340a3b1e06cffb6
diff --git a/xos/synchronizer/helpers.py b/xos/synchronizer/helpers.py
index b6b69d4..2f6382b 100644
--- a/xos/synchronizer/helpers.py
+++ b/xos/synchronizer/helpers.py
@@ -45,6 +45,9 @@
         except IndexError:
             raise DeferredException("ONU device %s is not know to XOS yet" % att_si.serial_number)
 
+        if onu.admin_state == "ADMIN_DISABLED":
+            return [False, "ONU has been manually disabled"]
+
         if pon_port.port_no != whitelisted.pon_port_id or att_si.of_dpid != whitelisted.device_id:
             log.warn("ONU disable as location don't match",
                      object=str(att_si),