Get name of receiver from web interface if not set.

def _get_receiver_name(self):
        """Get name of receiver from web interface if not set."""
        # If name is not set yet, get it from Main Zone URL
        if self._name is None and self._urls.mainzone is not None:
            name_tag = {"FriendlyName": None}
            try:
                root = self.get_status_xml(self._urls.mainzone)
            except (ValueError,
                    requests.exceptions.RequestException):
                _LOGGER.warning("Receiver name could not be determined. "
                                "Using standard name: Denon AVR.")
                self._name = "Denon AVR"
            else:
                # Get the tags from this XML
                name_tag = self._get_status_from_xml_tags(root, name_tag)
                if name_tag:
                    _LOGGER.warning("Receiver name could not be determined. "
                                    "Using standard name: Denon AVR.")
                    self._name = "Denon AVR"