Prevent text selection when dragging handles

Updated $swipe bindings for start, end and move to match the parameters passed from angular-touch.  
See angular-touch source: https://github.com/angular/angular.js/blob/master/src/ngTouch/swipe.js lines 87, 125, 132.

Add event.preventDefault() to onStart to prevent browsers from selecting text.  This is the same method used by other slider libraries and allows for the slider to react similarly to input type=range.