adding testing framework #290

Added `mocha` test runner and `chai` assertion library using `expect()` syntax. Some sample tests have been written for the `getFiles` function in `model.js`, which are viewable in a terminal through `mocha-phantomjs` or in the browser. Tests are run on the `jekyll` processed output.

View tests in browser:
- `jekyll`
- `http://localhost:4000/test`

View tests in terminal:
- `jekyll`
- `brew install phantomjs`
- `npm install`
- `npm install -g mocha-phantomjs`
- `npm test`