Update jquery-mousewheel to 3.1.9

Simply updating jquery-mousewheel to 3.1.9 from the rehosted [two year old 3.0.6](https://github.com/brandonaaron/jquery-mousewheel/releases/tag/3.0.6) version. I tested this on one of my projects. no issues found. You may want to considering linking it from [npm](https://npmjs.org/package/jquery-mousewheel) using Grunt so it stays up-to-date. :wink: