Update prepare module of centos-art.sh script.
    
    - Previously, prepare module was requiring you to install the package
      syslinux in order to get access to ppmtolss16 and lss16toppm
      commands. In CentOS 5.9 such commands are no longer part of syslinux
      package but syslinux-perl package instead. This update changes the
      package name from syslinux to syslinux-perl inside the package.sh
      file.