Update prepare module from tcar script.
    
    - Previously, the prepare module was conceived to produce final
      content inside The CentOS Artwork Repository itself. When The CentOS
      Artwork Repository was made installable through RPM, the content
      produced by the prepare module was already created as part of the
      installation process making the prepare module to loose its original
      purpose. Instead, the prepare module is redesigned to create the
      user's workplace.
    
      The workplace is the directory structure outside The CentOS Artwork
      Repository where the users store all the final files they produce
      using the models provided by The CentOS Artwork Repository.  The
      workplace contains the configuration files required to produce final
      content, as well as backgrounds images used to control the visual
      style of each model. The configuration files are symbolic links and
      connect the workplace with the installed repository. The backgrounds
      are created by the user and are specific to each workplace.