Refactoring

Hello Adam,

thanks for your nice plugin. I did some refactoring I thought may be helpful.
I have a few other modifications (e.g. added a component.json that points to my repository) that may not be suitable for a pull request, but nonetheless you may want to look at them.
Some other comments: it seems for jquery plugins a file naming like jquery-customselect.js or jquery.customselect.js seems to establish as a standard, you may want to think about renaming the file.
In addition, as most jQuery plugins are dual-licensed under MIT/GPL that may make it more flexible for people to use it.

Cheers,
Bernd