def manifest_icon(manifest, options = {})
      if manifest.icon
        external_icon manifest.icon, options
      else
        icon "question-mark", options
      end
    end
def manifest_icon(manifest, options = {})
      if manifest.icon
        external_icon manifest.icon, options
      else
        icon "question-mark", options
      end
    end
Public: Returns an icon given an instance of a Manifest. It defaults to
 a question mark when no icon is found.

 manifest - The manifest to generate the icon for.
 options - a Hash with options

 Returns an HTML tag with the icon.