----------------
- Use `getMultiAdapter` instead `restrictedTraverse` when getting the form
in the viewlet to speed up things.
[gbastien]
- Added attribute `button_with_icon` to a batch action, if set to True,
a particular CSS class is added to the button so it can be skinned
with an icon easily.
[gbastien]
- Register a `batch_actions.css` resource for basic styling.
[gbastien]