Add test framework scaffolding

[jflasher]

We currently do not have a framework in place for testing on project-seed. Came up after a recent meeting, we may want to change that. Initial question is which framework to go with?

@anandthakker has recommended https://github.com/sindresorhus/ava which had good initial support. Other big potentials are https://mochajs.org/, https://github.com/substack/tape, https://github.com/tapjs/node-tap, etc. Anyone have any strong feelings about this? If not, we can probably just roll with AVA to get something in place.

[drewbo]

No strong feelings. I've used tape and mocha very lightly in the past and they were fine. I gave ava a quick look and the docs are solid and it uses ES6 by default so I'm basically sold (although I'm sure its internal babel will cause us some problems in the future)

[dereklieu]

Happy to go with Ava or substack/tape. I find the syntax of tape a lot more pleasant to write than mocha, and the parallel processing of Ava is a big plus for big test suites.