cmd/coordinator/buildongce: set Scopes for DefaultClient

Otherwise it doesn't work.

Maybe it worked for Evan because he was on a GCE VM with the
right scopes itself. I am not.

Change-Id: Id29a3256a71c732cd9d63055c51b80a9f77b4211
Reviewed-on: https://go-review.googlesource.com/18982
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

cmd/coordinator/buildongce/create.go

@@ -140,7 +140,7 @@ func main() {
 
 	buildEnv.KubePassword = randomPassword()
 
-	oauthClient, err = google.DefaultClient(oauth2.NoContext)
+	oauthClient, err = google.DefaultClient(oauth2.NoContext, compute.CloudPlatformScope, compute.ComputeScope, compute.DevstorageFullControlScope)
 	if err != nil {
 		log.Fatalf("could not create oAuth client: %v", err)
 	}