Improve actions to support different displays for a single category

1. we should add a type category for different kinds of rendering. Examples:

rest document links (tabs)
bare output links (for instance links to Studio or Connect or nuxeo.com in default app)
command links / buttons / icons (could be treated as the same category, need to review differences between JSF buttons and links management)
popups opening a new window
fancy box calling JS code to display additional content.

2. as a result of fancy boxes support, need to add a "popupLink" attribute giving the xhtml template to include/display in the fancy box

Note that additional rendering customization should not be included in the action definition, but handled by templates rendering them (like CPSBoxes did).
As stated, providing BBB types for old categories and using ui:decorate tags as a start could be an easy solution. Using widgets to render actions may introduce limitations (like allowing to perform additional ajax actions when clicking on an action). that kind of mechanism is already used in the new widget type displaying a layout with a toggable mode (see NXP-8144)