This is a straight translation of the v1 API gRPC "plugin" to protogen.
Add a protoc-gen-go-grpc command. The preferred way to generate gRPC
services is to invoke both plugins separately:
protoc --go_out=. --go-grpc_out=. foo.proto
When invoked in this fashion, the generators will produce separate
foo.pb.go and foo_grpc.pb.go files.
Change-Id: Ie180385dab3da7063db96f7c2f9de3abbd749f63
Reviewed-on: https://go-review.googlesource.com/137037
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
