endpoints/getting-started-grpc: create a network bridge for GCE deployment (#846)
endpoints/getting-started-grpc: create a network bridge for GCE deployment (#846)

Signed-off-by: Wayne Zhang <bc786b8a4d6362cffdb954a38777b93c3461fd92@google.com>

Updates #841.
GoogleCloudPlatform/golang-samples,GoogleCloudPlatform/golang-samples,GoogleCloudPlatform/golang-samples