[Feature Request] Teardown script #6

While getting to know this CookieCutter, I've made several mistakes that resulted in an errant Lambda (and associated Cfn stack). It would be useful to have a teardown script that deletes the CloudFormation stack and optionally asks if we want to delete the artifact bucket.

I'm guessing its not too hard to do it manually though just by going into Cfn console and deleting the stack - which should clean up all the resources generated, but since we're at the command line doing bin/setup, bin/deploy, etc, a bin/teardown would be great too :).