VOL-1097 : Ofagent integration for voltha 2.0

- Created a common location for python based components
- Adjusted the ofagent component to interact with voltha 2.0
- Added streaming rpc methods for rcv/send of packets to voltha api
- Adjusted voltha.proto

Change-Id: I47fb7b80878ead060b4b42bd16cb4f8aa384fdb6
diff --git a/python/ofagent/protos/README b/python/ofagent/protos/README
new file mode 100644
index 0000000..65c5e93
--- /dev/null
+++ b/python/ofagent/protos/README
@@ -0,0 +1 @@
+Protoc-generated *.py files are populated here from Voltha via make