Reconsider format for commands.json and test files

[evmiguel]

After reviewing #73, the following questions have come up:

• Should commands.json that have been generated via script be committed?
• What should the process be for generating test files? And should those files be committed?

If this repo will be moving to a pattern where files are generated, I envision a test runner or automation invoking the creation of such files.

[spectranaut]

For me, the question here is: if these tests are declarative, we might want to get rid of the middle ground "test file" step and just have software that takes the CSV files and produces tests in an interface.