Story: Create a generic archiver service

[LynnMcRae]

SInce we have multiple archive endpoints, we want a reusable framework that only needs to be augmented to each endpoints storage API. Such a process would:

• fetch the latest archive bag from a shared location
• check the preservation policy to see if the current end point should be engaged
• check to see that the endpoint doesn't already have the current version of the object
• store the object appropriately
• update/create a record for the object in the PCC and log actions/results to Provenance database

Since archiving is an asynchronous process triggered by some form of messaging strategy, there will have to be a per-endpoint listener or a common listener that can invoke endpoints.

It is desirable to define a set of generic operations -- write object, read object, query status and other details from storage provider, etc -- in a generic API which maps to storage specific APIs.

[julianmorley]

Needs a way to clean up older versions of archive objects; if we already have the last two or three most recent versions, we don't need to retain the previous 10. We must also be mindful of the 90-day deletion rule used by both AWS and OCSA.