Move vendor/mocha to vendor/mocha.js (consistent naming)
Add chai.js as dependency for implementing assertions
Introduce extern for chai.js
Initial assert implementation for equals?

I decided to test similar form of assertion as Midje does. With complex
checks, the arrow (=>) splits the potentially complex forms visually into
two separate parts, which should improve readability.

Let's see.
Add simple (failing) test
Add assertion test