Performance gains for pipelining commands over the network.
Using tile38-benchmark and the -P flag it's possible to see 2x-10x boost
in requests per second.
Enabled TCP keepalive packets to determine if the connection is still
valid, and terminate if needed. It also helps with maintaining idle
connections.
Default to 300 seconds and can be changed by:
CONFIG SET keepalive 300
addresses #145: clients not being cleaned up properly
