CSS/Action Updates

Great plugin. I'm a big fan of a nice looking confirmation dialog that appears right there where I just clicked. I think it's a huge usability improvement. While adding it to my application, I made a couple of changes in my fork that I think offer a bit more flexibility when implementing the plugin.

1. I namespaced the CSS with the plugin name because `.question` is just a little to generic and it was getting in the way of my application's semantics.
1. I introduced the ability to call a function if the "Yes" button is clicked. I also allowed a the result of a function to generate the button text.

Thanks for taking a look. Hopefully you'll find these changes useful.