Move slide creation into JavaScript

So that we can easily create the slides based on some config
that we request from an HTTP API somewhere.
Improve style of full screen link
Upgrade frontend toolkit to 3.0.1

This one's for you, @easternbloc.
Merge pull request #16 from alphagov/tidying-slide-creation

Tidy slide creation
Add Google Analytics pageview tracking
Add Google Analytics event tracking

Sends 'heartbeat' event every half an hour