adds migrations, publish for admins
cant delete competition as admin
merge master
msg participants, remove cruft, hide delete if not owner
edit competition
merged master
user added as participant automatically, secret key not needed for admins
manage participants added
Merge pull request #630 from codalab/feature/worksheet_interface

 worksheet interface
fix misspelling.
Merge pull request #619 from codalab/feature/multiple-organizers

Multiple admins for a competition
Merge branch 'refs/heads/master' into feature/worksheet_interface