Updates example to be more dynamic

Moves all include files to an includes folder. Turns header
and footer into an include file. Moves menu into an include file
and automatically generates menu options by getting all the
topLevelSections from the KSS Parser.

Removes buttons.php and replaces it with a more generic reference.php
file that can be used to render any styleguide section.

Adds another css stylesheet to the project for display section headings
to make the example project have more than one KSS Top Level Section.