New Hello MontageJS + Set up

:warning: Only merge this after the new version of Minit, Digit and Montage got released on npm. :warning:

This is an update to [Set Up](http://montagejs.org/docs/montagejs-setup.html) and a complete rewrite of [Hello MontageJS](http://montagejs.org/docs/hello-montagejs.html).

ps. There are also some changes to the `figure` styling.