Summary:
Improve the build process by combining the CSS files, automatically
selecting font files to include, and building .tar.gz and .zip files.
Test Plan:
- Make sure tests work
- Make sure huxley screenshots didn't change
- Make sure zip and tar.gz files contain only files we want to distribute
Reviewers: alpert
Reviewed By: alpert
Differential Revision: http://phabricator.khanacademy.org/D13159