Import Jenkins website-commit configuration

Summary:
This stores the job config XML rather than requiring manual
configuration.  One possible issue is accidentally storing private
things, like the HipChat token.  I'm still looking for a way around
that.

Import Jenkins top-level configuration

Test Plan: Copied files from the working server.  The build passes!

Reviewers: csilvers

Reviewed By: csilvers

Differential Revision: http://phabricator.khanacademy.org/D2175