ENHANCEMENT add ability to download a file as a file download. The method does not pass through so if the file is very big, or latency is too long, a streaming approach would be required or the files should not be passed through via the SilverStripe controller.
MINOR add test download controller. Only accessible in DEV environment. call /[BaseURL]/DownloadController to see all available files (stored S3Files). Click on a link to download the file.