Add a parameter to take advantage of the new(ish) eventlet socket timeout
behaviour. Allows closing idle client connections after a period of
time, eg:
$ time nc localhost 9292
real 1m0.063s
Setting 'client_socket_timeout = 0' means do not timeout.
DocImpact
Closes-bug: 1371022
Change-Id: I9e7edcbf25ece61dc16b8cd5a8bef5ed9a14e3d6