Bug 1009883 - Implement Nightly First Run page redesign

To ensure the requests aren't aborted, all GA calls should use our [`gaTrack` function](https://github.com/mozilla/bedrock/blob/master/media/js/base/global.js#L135). [Here's a good example](https://github.com/mozilla/bedrock/blob/master/media/js/firefox/desktop/tips.js#L174).