Code Cleanup and Added Close Callback Function

Hey! Really like the simpleness of your plugin :)

On a project we were using your modal to open a video box. On close we needed to reset the video to keep it from playing and saving resources. Being what I found a common scenario I decided to fork it and add a callback after the close event.

This pull request is in case you like the implementation and wish to include it.

I also made some minimum clean-ups and code refactoring.


Credit is stated to you on future uses of my fork.

Hope you like it!
Gabe