E-commerce giant Amazon is shutting down its Quidsi unit, the parent company of sites like Diapers.com and Soap.com, after it failed to reach profitability, the company said Wednesday. Amazon bought Quidsi in 2010 for around $500 million in cash, according to a press release. The packaged deal came with other sites such as Wag.com (pets), BeautyBar.com...