Added grunt builds and support for data-preview-url, which allows the preview resource to differ from the link's href.

I added functionality that allows the preview url to be different from the URL on the anchor.

<a class="preview" href="/some/url" data-preview-url="/some/preview/url">Google</a>

I also added grunt builds and a basic grunt file to ensure that these changes make it into the minified js.

Is there any chance that you'd be willing to dual license this under a commercial use license (MIT, Apache, etc)?