Change structure of menus in header and add css classes

Split top-menu and filter-menu out from the nav because only the top-menu
is a nav. Put both inside a header and add css classes to the menus.
Highlight active state

Add the 'active' css class to the top-menu list item representing the
state you are currently in (or that best represents it, via parent state)
Merge pull request #14 from bdo-labs/newmenu-styles

Styling of the new menu