Update default design models:
    
        - Use CentOS release brands from revision 358.
    
        - Keep using CentOS symbol at 48x48 pixels, but change CentOS
          release brand to 72 pixels height. The width of CentOS release
          brand is calculated automatically keeping image ratio invariable.
    
        - Anaconda Prompt artwork uses CentOS release brand at 96 pixels
          height. There is no CentOS symbol on this artwork.
    
        - Both GDM and KDM use CentOS release brand at 490 pixels width.
          The height of CentOS release brand is calculated automatically
          to fit image ratio. In GDM case the 490 pixels width is a
          convenction to match the width of username/password entry. In
          KDM case, the 490 pixels width is used for consistency with GDM.
    
        - Remove CentOS phrase from Anaconda splash. Even this image is
          shown before any language selection, and using the CentOS phrase
          on it is not contradictory, I desided to remove it from the
          image in order to keep consistency among other Anaconda artworks
          that use CentOS release brand after language selection.
    
        - Inside GRUB's artwork the CentOS release brand is set to 32
          pixels height. The width of CentOS release brand is calculated
          automatically to fit its ratio. When positioning CentOS release
          brand in the screen, the CentOS phrase was temporally changed to
          letter ``C'' in order to use this letter's baseline as reference
          to position the entire brand.  The CentOS release brand is set
          at 10 pixels both on X and Y coordinates.