Update Product Planning - Document setup for PO candidates & POs created on demand via material schedule

[metas-dh]

• set a vendor (with a discount schema) as current vendor
• set up product planning for the resp. product: data planning needs to have Purchased:Y and Create Plan:Y

=> when there is demand from sales orders / production > QtyOnHand, purchase candidates are triggered

[metas-Kay]

Consult/recycle Java Client docs: DE: http://docs.metasfresh.org/howto_collection/Wie_konfiguriere_ich_ein_Produkt_f%C3%BCr_die_Produktion.html EN: http://docs.metasfresh.org/howto_collection/EN_tbd/How_to_configure_a_product_for_production_purposes.html