[ADD] URL shortener

TASK : https://www.odoo.com/web#id=8277&view_type=form&model=project.task&menu_id=3942&action=327
Here is the full method :

```javascript
start: function() {
    self.$el.on('click', 'a[data-action]', function(ev) {
        ev.preventDefault();
        var $content_item = $(this);
        self[$content_item.data('action')]();
    });
}
```

This method call the supposed method name inside the `data-action` parameter of the link. So if we have a link like this one :

```html
<a href="#" data-action="my_method">My Action Link</a>
```

It will call `my_method()`.

What if the link doesn't have a `data-action` param ? The JavaScript will crash. What we can do is to call this method only if the link have the data-action param, and that's what `a[data-action]` do.

Note : This is a modification by Christophe Matthieu.