Show gcloud output more frequently than one line at a time

[tswast]

When deploying an App Engine standard application, the output pauses for a while after

[INFO] GCLOUD: File upload done.

After a minute or so we get the line

[INFO] GCLOUD: Updating service [default]..............................done.

I believe the gcloud command is outputting the .s as a progress-indicator, but this does not work well with the plugin, which only displayed the line after it was completely done.

[chanseokoh]

This should be fixed in the appengine-plugins-core library. The library already has an issue for this.