Add support for StackId pseudo parameter

We need to add support for the StackId pseudo parameter, so we can reference the ARN of a stack in the template, currently we only support the StackName and Region parameters:

http://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/pseudo-parameter-reference.html

This is needed e.g for bug 1131666 where we wish to be able to specify the ARN for the nested resource to later be able to retrieve metadata for itself.