Add verbose logging

[kahkhang]

No description provided.

[nbiles]

+1

[ds0nt]

+1 to see error messages

edit: awesome script btw!

[katox]

Yes, the script needs some kind of output for debugging.

I had run the latest version and it stuck in the initialization stage of the master node for 2.5h. Then I killed the script. The machine was inaccessible via ssh -i ~/.ssh/id_rsa core@ip. It's hard to tell what's going on. I tried it on Ubuntu 18.04.1 LTS.