Features/font awesome

This moves our font files from `src/img` to `share/font` and adds font-awesome icons to the menu bar on (only, currently) the login page.

![RouteMaster_font_awesome_menu](https://f.cloud.github.com/assets/1088389/254063/f3227b06-8be9-11e2-95b4-184393feb77d.png)