Create Accessible menu

[andrewwoods]

Create an easy to install, two-level, accessible menu.

• create a mapping of color names to semantic names in SCSS
• Provide a Walker class to customize the main navigation HTML
• Provide a Javascript Module for the Main navigation
• Provide snippets for animating the menu - slide from left, slide down - without jquery

example semantic names in SCSS

$ancestor-selected-bg-color: $blue-dark;
$ancestor-selected-text-color: $white;