Add an extended TIMOUTidle setting to stunnel

This change affects the client mode of stunnel only. An
equivalent for the server needs to be added elsewhere.

Signed-off-by: Jon Ludlam <jonathan.ludlam@eu.citrix.com>
Merge pull request #153 from zli/xenserver/sanibel-lcm/HFX-1147

HFX-1147