Change test framework from Buster to Mocha and Mochify

- Add Mocha and Mochify dependencies
- Run tests on Node, PhantomJS and SauceLabs
- Remove obsolete test runner

I've simply converted the tests without touching the test implementation. Tests pass on Node and in Chrome. There are a few failing tests on PhantomJS and one on IE 9 and 10. To run tests in the cloud you will need a free SauceLabs account.

Mochify docs are here: https://github.com/mantoni/mochify.js
Details about how the SauceLabs stuff is set up can be found here: https://github.com/mantoni/min-webdriver

Have a look around and let me know what you think.