Provide bogus defaults to AWS driver...
Provide bogus defaults to AWS driver...

... so that we can run `bundle exec rake vagrant:test` without
kitchen-salt failing due to the missing envvars.

ministryofjustice/metrics-formula,ministryofjustice/metrics-formula,ministryofjustice/metrics-formula,ministryofjustice/metrics-formula,ministryofjustice/metrics-formula