EXP-430. Update tutorial end-to-end tests to test python script.

issue: https://jira.kiji.org/browse/EXP-430
review: https://review.kiji.org/r/1773/
SCHEMA-761. Update REVIEWERS in kiji-end-to-end-tests.

issue: https://jira.kiji.org/browse/SCHEMA-761
review: https://review.kiji.org/r/1813
EXP-437. Fix regression in the the Express music end-to-end test.

issue: https://jira.kiji.org/browse/EXP-437
review: https://review.kiji.org/r/1848