XOP-229: Make xenopsd using keep_alive.

Signed-off-by: Jerome Maloberti <jerome.maloberti@citrix.com>
XOP-229: Make rrd_updates uses keep_alive=true.

Signed-off-by: Jerome Maloberti <jerome.maloberti@citrix.com>
Merge pull request #996 from jeromemaloberti/XOP-229

XOP-229: Stunnel_cache fixes.