SEBA-497 delayering, Makefile, and tox for att-workflow-drvier

Change-Id: I5869c36b8b716cab02ae12a343969c4feeacf5fb
diff --git a/xos/synchronizer/event_steps/dhcp_event.py b/xos/synchronizer/event_steps/dhcp_event.py
index ab411f7..06abc5a 100644
--- a/xos/synchronizer/event_steps/dhcp_event.py
+++ b/xos/synchronizer/event_steps/dhcp_event.py
@@ -14,12 +14,10 @@
 # limitations under the License.
 
 import json
-import time
-import os
-import sys
 from xossynchronizer.event_steps.eventstep import EventStep
 from helpers import AttHelpers
 
+
 class SubscriberDhcpEventStep(EventStep):
     topics = ["dhcp.events"]
     technology = "kafka"
@@ -34,7 +32,9 @@
         si = AttHelpers.get_si_by_sn(self.model_accessor, self.log, onu_sn)
 
         if not si:
-            self.log.exception("dhcp.events: Cannot find att-workflow-driver service instance for this event", kafka_event=value)
+            self.log.exception(
+                "dhcp.events: Cannot find att-workflow-driver service instance for this event",
+                kafka_event=value)
             raise Exception("dhcp.events: Cannot find att-workflow-driver service instance for this event")
 
         self.log.info("dhcp.events: Got event for subscriber", event_value=value, onu_sn=onu_sn, si=si)