scripts: Print error value in case of action script fail

For easier debugging.

v2: Forward scripts messages to criu log using cr_system

travis-ci: success for scripts: Print error value in case of action script fail (rev2)
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>