Changes to go with the assessments A/B test

Summary: Adding some piping for the opt-out button

Test Plan:
It works! How do you even test the frontend?
         All the other buttons also work

Reviewers: marcia, james, alpert

Reviewed By: alpert

CC: jace, alpert

Differential Revision: http://phabricator.khanacademy.org/D3611