[Bug] Fix CreateObject() action

in file "device.c", function "prv_create_new_container_didl()"

- replace call to function:
gupnp_didl_lite_writer_add_item(...)
by a call to function:
gupnp_didl_lite_writer_add_container(...)

Fix issue: https://github.com/01org/media-service-upnp/issues/188

Signed-off-by: Christophe Guiraud <christophe.guiraud@intel.com>