Cannot use connection_retry and command_retry for KazooDriver

According to the documentation for the kazoo library,
to use the `connection_retry` or `command_retry` parameters of a KazooClient object,
it should be a `kazoo.retry.KazooRetry` object or dict type. [1]

However, there is no logic to parse this parameter in the tooz layer.
And when I tested providing the `connection_retry` and `command_retry` parameter to the Zookeeper coordinator url, those parameters are recognized as a string type and generated a default KazooRetry object.

[1] https://kazoo.readthedocs.io/en/latest/api/client.html