Add support for Transforms in CloudFormation templates

[rjd1]

Currently launching a CF stack via the cloudformation_stack type with a transform results in the error:
CreateStack cannot be used with templates containing Transforms.

There is great appeal for us to manage our stacks through puppet but all our templates utilize transforms. The primary use is with AWS::Include to load a separate template that contains all our mappings from S3, where they are centrally managed. It would be awesome if this was supported.