wrong behavior in children remove

Users may have rights for listing folder's content but not for deleting them. At this time, when a user ask the session for deleting the folder, the core session is filtering these children silently. The user don't have any feed-back from the system he didn't delete all the children he is expecting to.

The core session should not just ignore folders for which the users don't have the delete permission. An exception should be thrown indicating the missed condition.