Allow autoscaling group to support 'min instances in service' and 'max size' values that are Refs
Change AutoScalingGroup.MaxSize type to base_string to reflect support of Refs
Change AWSHelperFn to Ref. Also solves line length problem in travis.
Fixed line length issue with pep8.
Fixed logic issue.
Merge pull request #82 from andystanton/allow-asg-updatepolicy-to-use-refs

Allow autoscaling group to support 'min instances in service' and 'max size' values that are Refs