[DO NOT MERGE] Add plugin code

[Readme](https://github.com/UseAllFive/scrubify.js/blob/plugin/README.md)

[Video mapped to document scroll](http://useallfive.github.io/scrubify.js/document-example.html)

[Video mapped to div scroll](http://useallfive.github.io/scrubify.js/inside-div-example.html)

Might be safer to do `outerHeight()` here to take get the current computed height *including* padding and border. Optionally you can include margin too but you don't wanna do that. http://api.jquery.com/outerheight/