Changelog entry not generated during archive lifecycle management

[henxing]

On every change to a Media object, there should be a corresponding ChangeLog object that describes the difference between the two states. This happens in the REST endpoints, so when a media object is updated in archivemedia.py, requestrestoration.py, or finishrestoration.py, no ChangeLog object is created. Refactor the change log functionality into a helper method and add the change log function where it is missing.