Issue #40: Cancel scroll on mousewheel

Link to [Issue #40: Cancel scroll on mousewheel](https://github.com/durated/angular-scroll/issues/40)

I also wanted to look into cancelling the animation on scroll so I have added this in by binding a cancel on scroll function to the mouse wheel event when the animation starts, then unbinding the listener when the animation stops. 

Sorry for the space replacements, my Sublime is set up to remove trailing spaces. 

Also sorry no tests, I'm a Grunt man and Gulp is throwing errors with the karma plugin.