add simple blackbox test for Probe items

Change-Id: Ie0df664a2bec152ea7d537365df108a9da03d2ef
Reviewed-by: Christian Kandeler <christian.kandeler@digia.com>
make product.sourceDirectory available in Probe item

Task-number: QBS-393
Change-Id: I33c588fd0c00231db2ca4fa4f9b70a5b1f5bc18f
Reviewed-by: Christian Kandeler <christian.kandeler@digia.com>