Should the register command call the delete endpoint on SIGTERM?

[nkinkade]

@robertodauria: We have talked about this casually, but I wanted to open an issue so that we don't lose sight of it, since on the surface it sounded like a good idea. Should the autojoin client make a call to the Autojoin delete endpoint when it receives a SIGTERM and before shutting down?

This would solve a lot of the monitoring issues we have where Autojoin hangs on to an autonode for 14d before expunging the data.

On the other hand, it seems there is a chance that we won't need to manage the platform GCE VMs in the future, which alleviates all sort of issues, too.