VOL-1500 VOL-1475 Updated the remaining python containers in voltha-go to use pyvoltha and voltha-protos

Changed the build system to have separate flags for local pyvoltha and local protos.
Cleared out now unneeded python libraries and protos from voltha-go

PonSim was tested by launching the system-test-ponsim.yml and making sure the ponsim enables.
This was tested on docker-compose and k8s.
Let me know if there are other cases to test.

Change-Id: Ie2d5a19900fcfc93b96aba2981efb18fd9e649bb
diff --git a/python/ofagent/grpc_client.py b/python/ofagent/grpc_client.py
index 4a6d274..096d56e 100755
--- a/python/ofagent/grpc_client.py
+++ b/python/ofagent/grpc_client.py
@@ -27,9 +27,10 @@
 from twisted.internet import threads
 from twisted.internet.defer import inlineCallbacks, returnValue, DeferredQueue
 
-from protos.voltha_pb2 import ID, VolthaServiceStub, FlowTableUpdate, \
+from voltha_protos.voltha_pb2_grpc import VolthaServiceStub
+from voltha_protos.voltha_pb2 import ID, FlowTableUpdate, \
     FlowGroupTableUpdate, PacketOut
-from protos.logical_device_pb2 import LogicalPortId
+from voltha_protos.logical_device_pb2 import LogicalPortId
 from google.protobuf import empty_pb2