LDEV-2999: Rating check was comparing the wrong ids - it was comparing the real user id with the uid of the qa user table. If you were unlucky and had a user id that was the uid of another user in qa, then you could not rate their answer.
LDEV-3689: Once a spreadsheet is marked it cannot be changed by the learner. This is done by removing the save button on the learner interface and by checking the status in the save method (which is also triggered by the finish button).
