GhostWidget content appears in pages

The GhostWidget is intended to suppress the the field from being rendered in the page. You can see the license_info hint text in the +new project page. While the <input< was not rendered, pther part are. The probelm is that the widget attribute can and are set after the widget is created. So while the hint is an empty string in the class definition, it is not at the time of rendering. The page contains table rows with empty blocks elements that render as extra white space in the page.

    * The correct fix is to use the invisible attribute to indicate it should not be seen
    * And update the launchpad-form-macros to not render any markup if widget.hidden() is None.