Mounts a container or image referred to by identifier to
        the host filesystem.

def mount(self, identifier):
        """
        Mounts a container or image referred to by identifier to
        the host filesystem.
        """

        driver = self.client.info()['Driver']
        driver_mount_fn = getattr(self, "_mount_" + driver,
                                  self._unsupported_backend)
        cid = driver_mount_fn(identifier)

        # Return mount path so it can be later unmounted by path
        return self.mountpoint, cid