CORE-5042 Updates for DiskResourceInfo fields.

The service endpoint for this AutoBean is returning slightly a different format to be more consistent with other file listing endpoints.
Modified and Created fields for this AutoBean can just be a Date rather than a string or long.
CORE-5042 File field 'file-size' is now a long.
core-5030 changes for download contents
Refactor and cleanup of IPlantAnchor class.
CORE-4960
CORE-4876
CORE-4876: Continuing search-related unit test dev
CORE-4876: Ongoing unit test development