Clean up the analytics setup script a bit.

Summary:
Mostly I just separated stuff out into functions.  But I also updated
the gae sdk to match the actual version installed on the analytics
machine now.

Test Plan: Fingers crossed.  I'm scared to actually run this!

Reviewers: jace, chris

Reviewed By: chris

Differential Revision: http://phabricator.khanacademy.org/D8016