Feature #2375
Updated by Tom Clegg about 11 years ago
* Log object is added even if "update" does not actually change the database content (e.g., "node is still alive")
* Log object's "properties" attribute _(rename it, it's currently called "info")_ includes:
** timestamp of the change
** uuid of user making the change (usually same as modified_by, except delete and some updates)
** class name and uuid of the affected object (although these are also in log.object_kind and _uuid)
** update type (create, update, delete)
** etag of the new version (nil for delete)
** etag of the old version (nil for create)
** all attributes of the new version (nil if deleting)
** all attributes of the old version (nil if creating)
* modified_by is current_user (the user whose transaction is being logged)
* owner_uuid is system_user (this prevents users from deleting logs)