bytes as parameter for python 3

[gera2ld]

When I was using redis on Python 3, I have to pass bytes as value to connection.set. I think this is reasonable.
So when I found asyncio-redis requires a str as value, I think it's buggy because in such case, I have to transform a binary sequence into readable string before I can pass it to redis which will increase the length of data.

Sorry for the wrong issue, I just found it support encoders.