ipa-replica-prepare: Wait for the DNS entry to be resolvable
    
    It takes some time after the DNS record is added until it propagates
    to Bind. In automated installations, it might happen that
    replica-install is attempted before the hostname is resolvable;
    in that case the connection check would fail.
    
    Wait for the name to be resolvable at the end of replica-prepare.
    Mention that this can be interrupted (Ctrl+C).
    Provide an option to skip the wait.
    
    In case DNS is not managed by IPA, this reminds the admin of the necessary
    configuration and checks their work, but it's possible to skip (either by
    interrupting it interactively, or by the option).
    
    https://fedorahosted.org/freeipa/ticket/4551
    
    Reviewed-By: Petr Spacek <pspacek@redhat.com>