Ticket 556 - Don't overwrite certmap.conf during upgrade
    
    The certmap.conf config files were being overwritten with the
    default template during upgrade.  We need to skip writing the
    certmap.conf files if they already exist so config changes are
    not lost.
    (cherry picked from commit e63ad6840e4a9a62f3ffae27eaba1091653a1c50)