Poll for CloudFormation events to ensure update worked.
Improve CloudFormation deployment type's documentation
Only add Stage parameter if necessary
Support multiple stacks properly

Defaults to prepending a stack name where available and adds a parameter of the stack if in the list required by the template.

I've also made everything explicit about talking about CloudFormation stacks, which is horribly verbose, but I fear necessary.
Merge pull request #180 from guardian/pw-check-cloud-formation-events

Check cloud formation events