Major operations:
* Fix the go_package entries to be consistent, as the new tool
complains when it doesn't have a '/'.
* Regenerate with the new protoc-gen-go tool.
* github.com/golang/protobuf -> google.golang.org/protobuf
* proto.[Un]MarshalText -> prototext.[Un]Marshal
Change-Id: Ie1147bd2457fafb66ba555461b3bf14f0561a25d