pod: Allow to stop a pod in ready state as a special case
pod: Allow to stop a pod in ready state as a special case

Because we allowed to kill a container process even if the container
is not running, we have to allow the same thing at the pod level,
otherwise we run into some issues saying that we cannot stop a pod
which is not running.

Fixes #332

Signed-off-by: Sebastien Boeuf <90b401417360b1924ef3f520ddee932686110f85@intel.com>

containers/virtcontainers,containers/virtcontainers