py3: _httplib_request: don't convert string to bytes
    
    There is no need to encode hostname to bytes. UTF-8 characters must be
    encoded in different format in URL anyway and it causes only error in
    Py3. String must be unicode to support Py2.
    
    https://fedorahosted.org/freeipa/ticket/4985
    
    Reviewed-By: Christian Heimes <cheimes@redhat.com>
    Reviewed-By: Jan Cholasta <jcholast@redhat.com>