setupvm and upgradevm should require confirmation

[ocdtrekkie]

This is particularly egregious with setupvm, but I'd like to fix it for both. These commands overwrite existing app packaging files without any confirmation. In the case of setupvm it is basically a reset of your packaging efforts, upgradevm it is just going to force you to fix your app build for the latest VM.

Either way, we should probably put a quick "are you sure?" in here. We may also need to look at a flag or environment variable to skip these confirmations. While nobody is using it AFAIK, vagrant-spk auto is a thing that exists in the code that @paulproteus was building, and other situations where people have scripted calling setupvm may exist. (Nobody is currently scripting calling upgradevm yet because it doesn't exist yet.)