Bug fixing

[FI-Mihej]

http_client

1. Original code doesn't allow to set concurency=1.
2. There was division by zero problem in lua script.
3. In some situations lua script returns 'nan' in json and python json parser can't handle it.

asyncio_http_server.py

1. Original on_url() can't handle url in real world situations (when read() returns part of http request)