kiji-express-music: EXP-289. Fix express music tutorial for EXP-222

review: https://review.kiji.org/r/1354
issue: https://jira.kiji.org/EXP-289
commit: https://github.com/kijiproject/kiji-express-music/commit/84ce8e66860534f79a931eec21cb98b0f6027f09