Move first part into subdir
Chapter 18: Add TestCaseTest
Move was_run accessor to WasRun class, like it should be
Chapter 19
Chapter 20
Add assert method
Chapter 21
Chapter 22
Print all results for debugging
Chapter 23
Add test for teardown after test failure
Report exceptions during setup as test failures
Reduce duplication with new method TestSuite#add_all_test_methods