Introduce TOC for jQuery and basic TOC configuration

Adds toc - a jQuery Table of Contents Plugin and intiiates it for
use on the page
Add documentation
Setup some defaults in the plugin JS
Add some default CSS for the generated table of contents

This is very, very early. We'll need some sane defaults.
Add a GPL v2 or later license
Wrap script and style enqueue in a filter that defaults to false
Add a filter to generate a TOC on pages only
Merge pull request #1 from washingtonstateuniversity/initial

[PR] Add initial work for the TOC generator plugin