CRDB doesn't like large deletes. While testing in the POC environment we found that deletes on the serial_numbers table could take hours. This change limits deletes to 1000 at a time (configurable) to avoid blocking other queries.
Change-Id: I08455e25db1574579dd4d7b7125a08e9c913dff1
Creates a new chore, dbcleanup, which can be used for routine deletion of items from the satellite database and adds functionality for deletion of expired serial numbers
