Support other data formats in AsyncRedisManager for compatibility with node

[markwitt1]

Is your feature request related to a problem? Please describe.
I can't run a socketio server on node and on python and communicate via async_redis_manager pub/sub as python version uses pickle format that node doesn't have

Describe the solution you'd like
Support msgpack in AsyncRedisManager

[miguelgrinberg]

Running node and python servers together is not a supported feature. You may think that the difference in the format of the packets is the only one, but there are many more, because this was never intended to be a use case.

There is already a request to support other encoding mechanisms (see #850) but this is not going to allow you to do what you want.