Refactor exercise class
Rename test fixture for assignment test
Refactor tests
Refactor curriculum setup

Figure out how to test it so I can rewrite the smoke tests.
Clean up gemfile
Move requires into appropriate file
Fix test name

Two test suites with the same name will overwrite each other.
Add pry to test helper
Add more fake curricula to fixtures
Use fake curricula to fix API integration tests

Don't rely on real test suites for integration tests, as these change
all the time.