Allow sssd to ignore special users
    
    Currently /etc/nsswitch.conf has configurations like
    
    passwd:     sss files
    shadow:     files sss
    group:      sss files
    
    The problem is that to make sure that certain users could not be
    created in IPA (like nobody root etc), they were already created but
    in a restricted group. In order to allow sss to work for postfix, nfs,
    nobody and such, the sssd.conf needs to ignore them in the nss
    section. This adds a file which will do that.
    
    Signed-off-by: Stephen Smoogen <smooge@smoogespace.com>