Create some basic front-end unit tests

This creates some basic unit tests (using [QUnit](http://qunitjs.com/)) for the front-end JavaScript library I've dubbed `hourglass.js`. It covers utility functions and the API class used in the current demo.

The test suite runs client-side at [localhost:8000/tests/](http://localhost:8000/tests/). This obviously doesn't address the need for automated tests (in Selenium, for instance), but it's good enough for ensuring that the underlying code behind the initial prototypes works as expected. The API class, for instance, will be used heavily in the next couple of weeks.

Mea culpa: there are some CSS tweaks riding along with this PR.