Make navigation without lists

[joseluis]

Remove lists from nav elements, for more cleanliness and simplicity, and better compatibility with screen readers

Some links:

• http://css-tricks.com/navigation-in-lists-to-be-or-not-to-be/
• https://joshbetz.com/2013/02/listless-nav-menu-in-wordpress

[joseluis]

After further analysis I think it's better to leave things as they are. It has more benefits and it's kind of a standard.

http://codepen.io/chriscoyier/details/ztxvw