Change video transcripts to use locators instead of locations.

Part of STUD-870
Disable Peer Track Changes
STUD-1008
Merge pull request #1877 from edx/ned/hotfix-2013-12-04-with-temp-stuff-removed

Update 12/3 RC branch with the part of the hotfix we want permanently.
In OpenEndedModule latest_score and all_score calculate sum of rubric scores every time for ML grading.
ORA-72