We upgraded to the Hammer release of Ceph on Nov. 10, 2015 (and the release we're running now is Jewel). Versioning works, but with a couple caveats:
1) Versioning can only be used on buckets created after the Hammer upgrade date.
2) We don't have versioning features built into the DreamHost Control Panel.
Basically, you'll have to flip the switch using the API in another client besides the DreamHost Control Panel. The easiest way to do this is with Cyberduck - https://blog.cyberduck.io/2010/06/21/versioning/
You can also use the AWS CLI with this command
aws --endpoint-url https://objects-us-west-1.dream.io s3api put-bucket-versioning --bucket my-bucket --versioning-configuration Status=Enabled