Html5 uploader

I created a simple photo upload form with multiple file upload. Maybe this could be a useful addition to the contrib modules.

2 things which may not be pefect yet:
* As I don't know whether the Kohana Framework supports multiple file uploads via HTML5, I use the $_FILES array directly
* I didn't know how to add an arbitrary html code to the form, therefore I used a label on a hidden input field. Maybe someone can help with this. (see commit ae17980f677e27232dfae4a848918308fcfc31db)