Fix test_session_sd

Change-Id: Ib7ebe6720e3e5b914c5faa26c4c50ffbe226615a
Reviewed-on: http://gerrit.aldebaran.lan/43936
Approved: tfontenay <tfontenay@aldebaran-robotics.com>
Reviewed-by: tfontenay <tfontenay@aldebaran-robotics.com>
Tested-by: tfontenay <tfontenay@aldebaran-robotics.com>
Close RemoteObjects when unregistered

In some specific cases, this prevents deadlocks when RemoteObjects
are not closed properly (if the ROs are unregistered and the session
closes before the sockets die, the ROs are not closed and potential
futures will keep on waiting for answers that might not come).

Change-Id: Ic3726d2a30beed3d46a8ade50298a3f9cd91a127
Reviewed-on: http://gerrit.aldebaran.lan/43834
Approved: tfontenay <tfontenay@aldebaran-robotics.com>
Reviewed-by: tfontenay <tfontenay@aldebaran-robotics.com>
Tested-by: tfontenay <tfontenay@aldebaran-robotics.com>