[ 4222 ] Minor changes after code review

This is the initial commit for Persistence and Voltha restart.
It consists of the following:
1) Introduction of a store config id which represents the data of
   a Voltha instance.
2) The Coordinator service dynamically allocates a store config id
   to each voltha instance on startup.  It also reallocates the same id
   to another voltha instance in the event the previous voltha instance
   with that store id went down.
3) All voltha data is stored in Consul as KV
4) When a Voltha instance is started and get allocated a config id that
   refers to existing data (from an instance that went down), then it will
   load all the data from Consul into its own memory and start a reconciliation
   process.
5) During the reconciliation process, the necessary agents and
   callbacks are created as per the data.  A reconcile() API is also
   invoked on the adapters to perform their side of the reconciliation.
6) The Reconciliation process is implemented in ponsim OLT and ONU
7) A set of integration tests focussed on persistence and voltha
   restarts.
8) Fix a few bugs along the way

Change-Id: I8c2bbae3b2fc79d0afd8ce3b7b0be6bde93e492a
diff --git a/voltha/adapters/broadcom_onu/broadcom_onu.py b/voltha/adapters/broadcom_onu/broadcom_onu.py
index a424831..8adb0e8 100644
--- a/voltha/adapters/broadcom_onu/broadcom_onu.py
+++ b/voltha/adapters/broadcom_onu/broadcom_onu.py
@@ -97,6 +97,9 @@
         reactor.callLater(0, self.devices_handlers[device.proxy_address.channel_id].activate, device)
         return device
 
+    def reconcile_device(self, device):
+        raise NotImplementedError()
+
     def abandon_device(self, device):
         raise NotImplementedError()