Added purge monitoring to GCR cache

Pulled in Rickards Monitors utility for easier and collected monitoring of
components in the database.

Also, when purging will not purge the item at the the position where the
purge starts since that position will be the most recently put/updated
position so it doesn't make sense to directly purge it after put/update.
Merge pull request #1557 from tinwelint/1.9-gcr-monitoring

Added purge monitoring to GCR cache