Updated grid

* Added _config option for dynamic grid layouts.
* Updated several Sass variable names for better semantics.
Removed Slider. Pointed to HTML5BP hosted .htaccess
Updated .screen-reader class

Switched to more accessible HTML5 Boilerplate implementation.
Updated icon docs
Added `.list-inline` class.
Moved nav to _footer.html template

Simplifies documentation generation process, and makes a conversion to markdown easier.
Removed list-style attribute from ul and ol

Let's browser defaults do their thing.
Updated documentation