Update directory structure and file names for palettes of colors.
    
    - Previously, palettes of colors were stored directly in the root
      directory of tcar-palettes branch. This is inappropriate when the
      tcar-palettes branch is merged into the tcar branch. In order to
      provide a better organization, this update creates the Palettes
      directory and moves palettes of colors files into it.
    
    - Previously, palettes of colors file name didn't include the centos
      word in their names. Now they do.
    
    - Previously, the CentOS default palette didn't include the
      hexadecimal representation of the color. This update combines colors
      from Ubuntu and Tango palettes provided by Inkscape-0.47 into CentOS
      default palette and adds the hexadecimal representation of them.