jQRangeSlider also depends on jQuery UI mouse

Instead of using the provided `jquery-ui-1.8.16.custom.min.js` file, I'm using my own custom build. In doing so, I realized that jQRangeSlider also expects jQuery UI Mouse to be available. I've added this to the Readme, but would you mind also adding this to the documentation?
Merge pull request #131 from seanparmelee/patch-1

jQRangeSlider also depends on jQuery UI mouse