Changes link style to be visible on last slide in demo
Adds link to Mark's bespoke.js github project.
Now require version 0.4.0 or above of Bespoke.js so we can support deck.slide() returning the index of the active slide.
Initial refactor to support easier unit testing.

This may change again given the newer structure of Bespoke.js that supports references to plugins.
Adds support for navigating to a specific slide index.

This includes support for transitions to play when using the bespoke-loop plugin. As reported by https://github.com/xam1311 in https://github.com/ebow/bespoke-fx/issues/3