Make Voltha/OFAgent Ctrl-C terminatable

Change-Id: I8d64b126d8d8d6f368d6cc236b2293fbcd108416
diff --git a/ofagent/connection_mgr.py b/ofagent/connection_mgr.py
index 479bf4e..71318af 100644
--- a/ofagent/connection_mgr.py
+++ b/ofagent/connection_mgr.py
@@ -115,7 +115,6 @@
         log.info('Acquired a grpc channel to voltha')
         return channel
 
-
     @inlineCallbacks
     def get_list_of_logical_devices_from_voltha(self):
 
@@ -126,7 +125,7 @@
                 devices = stub.ListLogicalDevices(Empty()).items
                 for device in devices:
                     log.info("Devices {} -> {}".format(device.id,
-                                                            device.datapath_id))
+                                                       device.datapath_id))
                 returnValue(devices)
 
             except Exception as e:
@@ -136,7 +135,6 @@
             log.info('reconnect', after_delay=self.voltha_retry_interval)
             yield asleep(self.voltha_retry_interval)
 
-
     def refresh_agent_connections(self, devices):
         """
         Based on the new device list, update the following state in the class: