Inline message styling

[laryn]

There are some inline messages in various places (such as the dirty form warning and notification on the dashboard) that still have default styling:

[laryn]

It looks like there are places where messages are manually built, so we probably need to account for the Backdrop structure and classes. e.g.

    if (empty($updates)) {
      $panel['up_to_date'] = array(
        '#type' => 'container',
        '#attributes' => array('class' => array('messages', 'status')),
      );
      $panel['up_to_date']['message'] = array(
        '#markup' => t('Your site is up to date.'),
      );
    }

[laryn]

It's a little duplicative but it's the best way I could think of at the moment to account for both structures: