properties config - provide checksum read status for properties

When properties are first applied or updated, seeing the checksum of the applied content allows verification that the application has completed.
On reload/reapply, where there is a period before the broker detects the need to update, the status can provide a mechanism to verify when changes have been applied.

To this end, I will add an alder32 checksum field to the properties status and apply the same pattern to the re-loadable properties from the jaas login modules.