Move normalize_hostname to where it is expected
    
    Commit 3d71c43504ea7837ea14bb9dd4a469c07337293f broke
    ipa-client-install by importing normalize_hostname from the wrong
    module.  Move the function.
    
    https://fedorahosted.org/freeipa/ticket/5976
    
    Reviewed-By: Martin Basti <mbasti@redhat.com>