Add sample Cloudformation or Serverless config

[Sleavely]

It would be useful to have a minimal template for publishing the Lambda with Cloudformation or Serverless.

As an example, this one could be used, although there's heavy reliance on defaults and (to me) unknown behavior when it comes to IAM and the likes:
https://github.com/awslabs/aws-cloudformation-templates/blob/master/community/services/Lambda/SAM/template.yml

Alternatively, this one is a bit more verbose but may be restrictive or provision more resources than needed:
https://github.com/awslabs/aws-cloudformation-templates/blob/master/aws/solutions/lambda-backed-cloudformation-custom-resources/get_latest_ami_id/deploy_get_latest_ami_id.yaml