Boto3 rewrite of cloudformation module
Boto3 rewrite of cloudformation module

- removed star-imports, which wasn't possible in Ansible 1.x
- boto doesn't have any of the modern features (most notably, changesets), so this rewrite goes all-in on boto3.
- tags are updateable, at least in boto3. Fix documentation.
- staying with "ansible yaml to json conversion" because I'm trying to keep this scoped properly. The next PR will have AWS-native yaml support.
- documented the output. Tried to leave it backwards-compatible but the changes to 'events' might break someone's flow. However, the existing data wasn't terribly useful so I don't assume it will hurt.
- split up the code into functions. This should make unit testing possible.
- added forward-facing code: 'six' for iterating, started using AWSRetry, common tag conversion.
- add todo list
- Pass `exception` parameter to fail_json

thaim/ansible,thaim/ansible