Update moin-1.5.9 visual style customization.
    
    - Previously, images affecting the visual style were stored inside
      Moin directory structure. This update changes the screen.css file to
      use images affecting the visual style from /var/www/webenv/images
      location instead, using the /webenv http alias.
    
    - Previously, the logo image used in the wiki was an entire image
      composed of two components: The CentOS Logo and The Wiki Logo. This
      update splits the logo image used by Moin into two separate images:
      One for The CentOS Logos and other for The Wiki Logo. This helps to
      reduce the amount of bytes transfered in image requests from browser
      to server (e.g., the web browser makes use of its cache to display
      The CentOS Logos for all requests except the first one).
    
    - The common directory was removed from this customization. The wiki
      configuration file was updated to use logo images from
      /webenv/images/ directory instead of /pub/ directory. There are some
      images specific to moinmoin that are not referred from
      /webenv/images directory yet (e.g., emoticons).