Fix #16.
Fix #16.

The application must wait until Write() completes before
calling WritesDone() and must wait until the creation of the
asynchronous stream completes before making the first Write()
operation.  I believe this behavior changed with more recent
versions if grpc and that is why the program used to work.

GoogleCloudPlatform/cpp-samples,GoogleCloudPlatform/cpp-samples,GoogleCloudPlatform/cpp-samples,GoogleCloudPlatform/cpp-samples