Python asyncio client inconsistent

[e-geist]

Hey,

I noticed some inconsistencies when using the v3 code generator for Python with the library asyncio:

• refresh_api_key_hook is not awaited, although if the rest other requests are async, this function will probably also be
• urllib3 logger is configured although it is not used
• urllib3 is still used for encoding BasicAuth header although aiohttp also provides a possibility for this
• urllib3 is still a dependency although it is not really needed (if previous point is resolved)

The same problems probably also apply for the generation of the tornado, but I don't have any experience with it and can therefore not confirm it.