Get rid of all fetch_logs logic.

Summary:
I'm keeping around greplogs for the moment, and also
tools/archive_to_s3.py which I don't know what it is, but otherwise I
got rid of everything I could find that deals with fetching and/or
analyzing logs from appengine.

Test Plan: Fingers crossed.

Reviewers: jace, chris

Reviewed By: chris

Subscribers: mattfaus

Differential Revision: http://phabricator.khanacademy.org/D8741