"validFrom" and "validUntil" fields in a ProductDiscount

We have introduced validity periods on Product Discounts to support discounting a (range of) products within a given time frame. Instead of activating product discounts manually, we now allow promotion planning in advance. Please consider that it can take some time to recalculate product discount values. Many discounts with the same validity values may take up to a few minutes to being live.

• [API] Added validFrom and validUntil fields in a ProductDiscount.
• [API] Added "setValidFrom" and "setValidUntil" update actions for a ProductDiscount.