Added link (<a>) support

Like described in the issue #27 I wanted to support binding on links. And I didn't want to give you extra work to do ^^

You can now bind intense on <a> 

- It can use href instead of data-image
- It can use title instead of data-title
- it still use data-caption for caption
- if binded on a A tag Intense will prevent Default event (so the link wont redirect)