Add Angular JS tests via Testem, powered by Grunt

Now run `grunt test` to compile the TypeScript to JavaScript and fire up the Testem server. Unfortunately, Testem in "run" mode is continuously blocking, so the `watch` task doesn't appear compatible. Ideally, the `testem` Grunt task should watch file changes, recompile the TypeScript, and run the Testem tests, ideally with PhantomJS instead of an actual browser. A tiger for another day, perhaps.