Sync fork with upstream PR to ensure better compatibility with other packages / libraries (allow more grpcio versions)

[berndverst]

Please update this fork once this PR is merged in upstream microsoft#36

The protos need to be compiled with an older grpc / protobuf version for support with a wider range of grpcio versions, which itself is necessary to be compatible with many more third party library / packages that pin grpcio versions.

[elena-kolevska]

Addressed in #6