Added support for HTML5 data attributes

Added support for HTML5 data attributes. Here is the equivalent for each option: 
* `closeAble`   -->  `data-close-able`
* `animation` -->  `data-animation`
* `showIcon`   -->  `data-show-icon`
* `closeOther`   -->  `data-close-other`
* `slideSpeed`   -->  `data-slide-speed`
* `activeIndex`   -->  `data-active-index`