Made the instance of SwipeSlide available

Attached using $.data - but only if the zepto data module is installed
Demo

Had to include a new version of Zepto because of the data module I'd
downloaded. I'm assuming that if you are using an older version of
Zepto, you can use an older version of the data module and everything
will work ok.
Merge pull request #13 from Trolleymusic/master

Exposed the instance of swipeSlide
Merge pull request #1 from max-power/master

Add PR #13 from source repo - adds a new demo file.