Trigger aws-cpi pipeline on stemcell bumps
Trigger aws-cpi pipeline on stemcell bumps

- run bats when we get a new stemcell to ensure package dependencies
haven't broken

[#174425880](https://www.pivotaltracker.com/story/show/174425880)

cloudfoundry-incubator/bosh-aws-cpi-release,cloudfoundry-incubator/bosh-aws-cpi-release,cloudfoundry-incubator/bosh-aws-cpi-release