PrimeTime: Amazon extends Whole Foods discounts to Prime subscribers, makes Prime Pantry a monthly membership, announces partnerships between Amazon Dash and WePlenish, AmazonFresh and SideChef; Costco holds out with strong membership model; “Amazon’s Choice” label grows in significance

The latest news on everything Amazon   Amazon is extending its Whole Foods discounts to Prime customers who will now save 10% on featured items—marketed as Prime Member deals in store—and on on-sale products at the grocery store in a…