Demo new testing suite: Mockable models, Quick, and Nimble

[brendanlensink]

We don't necessarily need to merge these changes, but given all the work we've been doing recently researching ways to level up our testing suite, I thought it might be handy to see some of those changes in action...

3 major components here:

1. Quick - gives us the Rspec-like testing language, using things like describes, it, beforeEach, etc...
2. Nimble - matcher functions like expect.to.equal, etc
3. Factory Bird - our own library that adds the Mockable protocol, replacing the TestData property wrapper