Moved file to tools and added comments from Jace's review.

Implemented Jace's requests from:  http://phabricator.khanacademy.org/rAb7c2439051e1ff24de71842889389f14260b49ba

Test Plan:
run a test script and make sure it still works

Auditors: jace, chris
Merge branch 'master' of github.com:Khan/analytics