Split repositories and GPG keys out into subpackages
    
    This makes it possible to support CentOS clients entirely from
    Spacewalk or Foreman controlled repository sources.
    
    The inclusion of the existing repos in the release package meant
    that all clients always have a way to access unfiltered repositories,
    which is not necessarily permitted for managed workstations.
    
    Separating the repository configuration out makes it very easy to support
    the mass managed case without causing hiccups and accidental breakage at scale
    with these kinds of platforms.
    
    In addition, this brings us in alignment with upstream Fedora in how repository
    definitions are shipped (precisely to support this use-case there).
    
    Signed-off-by: Neal Gompa <ngompa@centosproject.org>