Confirm before deleting prod

[symroe]

psql:
COMMENT ON DATABASE wdiv IS 'env:production';

Then run teardown --all

[coveralls]

coverage: 71.764% (-0.3%) from 72.035%
when pulling 9b70dd3 on dont-delete-prod
into 981bc9b on master.

[symroe]

Of course this is a proof of concept, I think it needs some cleaning up into something more generic, and maybe it needs to be added to some other places too.