Add sipport for Pipelining

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A Request/Response server can be implemented so that it is able to process new 
requests even if the client didn't already read the old responses. This way it 
is possible to send multiple commands to the server without waiting for the 
replies at all, and finally read the replies in a single step.
Redis supports pipelining since the very early days, so whatever version you 
are running, you can use pipelining with Redis.

There should be something like the batch request, which remembers the order of 
commands and places the results in accordance with this order.

Original issue reported on code.google.com by [email protected] on 14 Jan 2012 at 3:55