v0.21.2

storage: namespacing fixes (#13)

* storage: pluginstorage layer namespacing fix

`PluginStorage` abstraction layer should not re-namespace a key
if it is already namespaced. this is to support using keys directly from
`find_keys` with `PluginStorage.get`, et al.

* tests: update expect mock; only test on py38

* tests: create_redis_pool should return redis_client fixture

* storage: support str and bytes in key namespacing