Cloud storage output

[CaptainCodeman]

Make it easy to export data to cloud storage with the framework managing files etc...
Utilize cloud storage file chunks to rollup slices into shard, shard into namespace, namespace into job
Makes it easy to write - slices own their own file and can just overwrite in the event of a retry
Possible limitation is how many times files chunks can be combined (a bizarre limit of cloud storage, I can only imagine to protect against some runaway fork-bomb situation)