Add all-in-one, backup command

The backup command manages the process of:

* Listing a bucket.
* Looking up the last listing of that bucket.
* Doing a diff of the last listing (if it exists) with the current listing.
* Doing a sync on all the key from the diff.
* Persisting the new listing, along with ok/fail listings, to a 3rd S3 bucket (perf bucket for instance).

r: waiting for the metrics/logging PR to be cleared..