(bug 44181) Add Echo notification for instance deletions

There's also some code in here for bug 44180 - Add Echo notification for instance build completions
And bug 44179 - Add Echo notification for instance reboot completions

That's not done yet though. Will probably follow up with another change for those.

Change-Id: I6b70a600cd26b88ca92976e34eae7a3e1a5e8c39