* Allow different fields to be written out to the metadata log and the
statcache file.

* Implement a scheme for cleaning metadata log segments when metadata is
re-used.

* Improve the interface for remote upload scripts.  The current
interface is preliminary and is subject to change.

* Continue to investigate schemes for adding parity blocks for error
recovery.

* Switch over to a new hash algorithm beyond SHA-1, probably SHA-256.
(The system is designed to allow this, but see how it works in
practice.)

* Add snapshot deletion to cumulus-util, with some simple way to specify
what snapshots to keep so that automatic snapshot pruning can be done.