Rspec

[jduss4]

Switches from minitest to rspec for the test suite

You can take or leave this change, because I didn't consult anybody there before I decided just to do it!

A couple things to be aware of:

• I started an adr folder in docs which stands for "architectural decision record." We are using these at my current job and I really like them as a way to keep track of why we did things and when.
• I actually do think rspec will probably be better for testing out the API long-term, not that I was just changing things for kicks and giggles
• I didn't refactor any code in the tests beyond a few changes of descriptions and that sort of thing