Modify PHPABTest to work with Piwik

There is a framework for A/B testing in PHP at [[login to view URL]][1]. It currently has a function. It has a function to insert the Google Analytics code (see <[login to view URL]()>). This project is to add a new function that acts similar to the Google Analytics ones, but inserts the proper code to use the Piwik analytics software (<[login to view URL]>)