Update jenkins configs

Summary:
Notable updates:
- New admins.
- Allow non-admins to promote builds.
- Append 7-character GIT sha to build names where sensible.
- Builds must request secrets.py explicitly from build-make-target.sh
- website-allcheck now runs 3 times on weekdays.
- website-allcheck and website-commit now cap the number of lint
  failures sent to HipChat to 10 to avoid spamming.

Test Plan:
Ran fetch_jenkins_config.sh and am committing the results. This config
is already live.

Reviewers: csilvers

Reviewed By: csilvers

Differential Revision: http://phabricator.khanacademy.org/D4169