certprofile: add option to export profile config
    
    Add the `--out=FILENAME' option to `certprofile-show'.  When given,
    it exports the profile configuration from Dogtag and writes it to
    the named file.
    
    Fixes: https://fedorahosted.org/freeipa/ticket/5091
    Reviewed-By: Martin Basti <mbasti@redhat.com>