ENG-4576: When scanning snapshots for recovery, include the catalog
file.  When evaluating snapshots for complete-ness, check for the
presence of the catalog file and a valid CRC.
ENG-4576: Add the catalog jar file pass to SpecificSnapshotFilter for
consistency's sake, even though the current callers don't need the
catalog.
Merge pull request #464 from VoltDB/eng4576

ENG-4576: Include catalog sanity checks in snapshot completeness criteria