Use web notifications for betterifying your TDD

If your browser supports web notifications a new `Notifications`
checkbox will appear in the toolbar menu. When checked a `Fail`
notification will show when any tests have failed and a `Pass`
notification will show when all tests are green. Tomsters added for
scale.

![screen shot 2014-05-23 at 9 35 16 pm](https://cloud.githubusercontent.com/assets/18524/3073439/3677a5de-e2ec-11e3-8a76-461e0d1151dc.png)
![screen shot 2014-05-23 at 9 35 43 pm](https://cloud.githubusercontent.com/assets/18524/3073440/3ed378e8-e2ec-11e3-98e8-1045e941730e.png)