Issue with account IDs that begin with the digit 0

[nebffa]

Hey, awesome repo you have here, but there's one small issue with it:

You have some lines like provider_arn = "arn:aws:iam::" + str(${AWS::AccountId}) + ":saml-provider/" + provider_name which cause an error when you have an account ID beginning with 0. Python barfs on it, so I reckon it would be easier to do provider_arn = "arn:aws:iam::" + "${AWS::AccountId}" + ":saml-provider/" + provider_name