Fix reveal/hide button rendering

[avsm]

Right now the buttons are too small, but are rendered manually using CSS.

The reveal/hide logic can be done directly in Zurb using the helper classes (including better support for touchscreens), and I've integrated Font Awesome for the icons. The icons will no doubt be useful elsewhere other than just these buttons, so I'll push a change to integrate them. I won't modify your JavaScript until I'm back, as it would be good to nail down how we want it to work rather than messing around too much in this code. We should be able to get a responsive design that collapses the module includes, as you suggest.

See #84 for more discussion.