Shadow dom support

[lukawski]

Hello,

First of all thanks for great project! It was wonderful idea to create core for carousel which might be extended to become very advanced solution.

I'm currently working with Polymer and Web Components. I think it might be a good idea to provide support for shadow dom .

For example let's say I have carousel-siema element. Inside its shadow dom I have div element with id siema. And inside that I have slot. It acts as an insert point for elements that I wish to have inside carousel. And this piece of code: [].slice.call(this.selector.children) is not gonna work as those elements are not div#siema children.

If you are okay with that I have an idea how to solve this. It would require changing one line of code and adding two options to config object. But if it will break "lightweight and simple carousel" rule then I understand.