Sync Jenkins job configs

Summary:
This updates the version of the HipChat plugin used and turns on
notifications for website-allcheck. Also, git settings have moved into
global config.

Test Plan:
These jobs are running live on jenkins.khanacademy.org, I just pulled
down the live configs with:

  $ ./fetch_jenkins_config.sh

Reviewers: desmond

Reviewed By: desmond

Differential Revision: http://phabricator.khanacademy.org/D2728