Fetches all current container names from the client, along with their id.

def refresh(self):
        """
        Fetches all current container names from the client, along with their id.
        """
        if not self._client:
            return
        current_containers = self._client.containers(all=True)
        self.clear()
        for container in current_containers:
            container_names = container.get('Names')
            if container_names:
                c_id = container['Id']
                self.update((name[1:], c_id)
                            for name in container_names)