Magento, the ecommerce platform, launched in 2007, grew dramatically, and was acquired by eBay. When eBay divested PayPal in 2015, it also sold Magento to a private equity firm. Magento’s C.E.O. is now Mark Lavelle, a seasoned technology executive who co-founded Bill Me Later, the payment service. I spoke with him recently to discuss Magento and the state of ecommerce generally.