Fix up the ora2 scores affected by the track changes bug.

  For affected assessments:
    - Sets PeerWorkflowItem.scored = 0 if currently = 1
    - Recalculates the score for the submission
    - If new score > old score, update the Score.points_earned with the new score
+1 on @jrbl's comment - let's soften.  How about this?: "This submission may have been incorrectly scored, due to a system error related to this assessment.  This assessment will now be discounted, provided that doing so will not lower your score."