Use .on() and .off() instead of .live() and .die()

The playlist plugin is now using .on() and .off() instead of .live() and .die(). Thus the plugin requires jQuery 1.7+.

jQuery 1.9+ will drop the support of deprecated code. As jQuery 1.7 has been released a while ago, we can simply drop support for older jQuery version.

I hope this will help :)