Force ElastiCluster to re-authenticate on Google Cloud #650

(Originally reported by @monajemi in #626)

Also, @riccardomurri is there a way to force elasticluster to authenticate anew? I ran into similar problem and it is petty annoying. I could not figure out what was happening, so I had to set GOOGLE_APPLICATION_CREDENTIALS manually and mount .config. I have been using firebase functions lately and that might have caused some auth issues although I logged out. I could not figure out what was the problem.