Update local-only/update_local.sh and css/khan-site.css

Summary:
I modified update_local.sh to work with the latest version of kake, and ran
it to update css/khan-site.css

Test Plan:
 * python -m SimpleHTTPServer 7000
 * visit http://localhost:7000/exercises/adding_vectors.html
 * everything looked fine
 * crossed my fingers

Reviewers: csilvers

Reviewed By: csilvers

CC: eater, alpert

Differential Revision: http://phabricator.khanacademy.org/D5559