Request: adding a tests/ directory

[dylanirlbeck]

Thank you for this example repo! It's been a huge help so far writing my own library. I do have a "feature" request, though; if one of the maintainers gets time, can you give an example of writing tests for each platform? Right now I'm struggling to find the best way to organize both BuckleScript tests (written with bs-jest) and native tests (written with rely). I feel like this could be a huge help, especially for beginners like myself.

Thanks in advance!