Added Destroy Method.

Hi Mark,

Your plugin, scrollup, is excellent. Thank you for your hard work. I hope you would consider integrating this change. Please let me explain what it is.

I had the need to destroy this plugin properly. This was driven from the following scenario: I have a Light Box plugin that occupies the full screen, but when it is launched from the bottom of a page. The scrollup plugin produces a button with a z-index high enough to put it ontop of my light box. My solution was to add two events to the light box. One that executes when it is created, the other, when it is destroyed. I then attach a listeners to the lightbox that destroys or creates the scrollup appropriately. I would have added a qunit test, but there is none in the project. I compressed the file with nodejs uglify and added the change to the change log. I had considered changing the zindex, but that wouldn't have helped anyone else.

Best regards,
Philip A Senger