Fix bug 1012899: Update homepage with operator / manufacturer buttons.

This isn't quite complete; still waiting on confirmation of what text to use for the Maintain section link, and for whether we want to hide the maintain section or not.

This makes a few stylistic changes to make the homepage match the mockup from [bug 1014688](https://bugzilla.mozilla.org/show_bug.cgi?id=1014688) as well as adding two buttons that reveal different CTAs when selected.
Should this string be wrapped for l10n? Also, the arrow can be done with CSS and not hard-coded.