Fix an exception in the kafka client. Update gitignore to ignore
only proto files generated by Voltha.

Change-Id: I54b1b5e428a918ab20e564b55176942d0bc0facd
diff --git a/.gitignore b/.gitignore
index e1660b3..0b66ada 100644
--- a/.gitignore
+++ b/.gitignore
@@ -31,10 +31,11 @@
 adapters/venv-darwin
 
 # Protobuf output files
-**/*_pb2.py
-**/*_pb2_grpc.py
-**/*.pb.go
-**/*.desc
+python/**/*_pb2.py
+python/**/*_pb2_grpc.py
+python/**/*.desc
+protos/**/*.pb.go
+protos/**/*.desc
 
 # Editors
 *.bak