Move from jQuery Star Rating to jQuery Raty.

jQuery Star Ratings isn't compatable with jQuery 1.9 and hasn't been updated in over a year. Specifically, it uses browser.msie which is now deprecated.

jQuery Raty is under active development and has a much nicer API allowing us to integrate backbone more easily.

Swapped the libraries and made necessary changes in view.

Also, removed the cancel button (simplicity FTW!) and avg. star rating no longer displays on initial load. Ability to toggle both are commented out but in the model.

Note: @dannychapman, this plugin uses two images (`/img/star-on.png` and `/img/star-off.png`) rather than a single sprite and may require a slight coat of paint.