Add support for Python Twisted (txRedis)

[jacek99]

The current Python support uses blocking I/O.
It would be great if an option existed to use txRedis, which is the non-blocking I/O Python Twisted implementation.

[nfarring]

Hi Jacek, yes I agree that it would be great to be able to use txRedis. I have not yet had a need to use Twisted in my recent projects but maybe someone out there has? If so then patches would be welcome!