CloudFront use regional DNS name for S3 Buckets

[roleyfoley]

Expected Behaviour

When configuring a cdn component with an S3 or SPA backend the domain name listed should be the regional domain name of the bucket

Current Behaviour

We currently use the global name which can have issues within initial deployments due to the time it takes for the S3 bucket to global DNS registration to replicate

Possible Solution

Update getCFS3Origin to use getReference and use the RegionalDomainName attribute of the bucket if it is available

Context

Resolve issues identified here https://stackoverflow.com/questions/38735306/aws-cloudfront-redirecting-to-s3-bucket