Copying item to the data attribute of the span

Added `item` to "data-character" a custom HTML 5 data attribute of the span. This can then be called by pseudo elements using `content: attr(data-character);`.

This works for my [use case](http://codepen.io/alienresident/pen/mhqrj) but I think it would be more useful to add `data-{method}="'+item+'"`. So you could have data-character, data-word, data-line attributes depending on what method(s) you used. I am not sure how to do this.... 

It may also be useful to call this additional code only if you want it.Perhaps by calling an additional argument? 

Thoughts?