Release notes 12-16-14

@srpearce @fredsmith  @explorerleslie 

need to complete by 11:00

FYI @lamagnifica @catong 
...files that course staff...
should have: does this apply only to files that get uploaded on the Files & Uploads page, or any files in the course (I'm thinking of video of course)
nice to have: what this limit will do (reduce failed or unreadable files?)