v4.2.0

Added

• Added support for ingest actions, specifically "truncate collection". This is enabled
  by setting ENABLE_INGEST_ACTION_TRUNCATE to true.

Changed

• When being ingested, Items and Collection without a links array will not be rejected,
  but will have the field added.

Removed

• From ingest.js, removed combineDbObjectsIntoBulkOperations and writeRecordsInBulkToDb
  functions, as they have not been used since version 2.0.0.