No e2e tests for review materials

[jkeat]

Currently, we don't have e2e tests for review materials

• Each subject should link to its review materials
  • http://localhost:8080/training
• Each subject's material should be viewable
  • e.g. http://localhost:8080/training/review/algebra
• A subject without review materials should show the message: Sorry, we do not currently have ... etc
  • e.g. as of 5/26, no review materials for chemistry: http://localhost:8080/training/review/chemistry