Since its founding in 1993, Chipotle has begun to emerge as a kind of rock star in the food world. It’s fast food, but it’s fresh, and the company’s "food with integrity" philosophy has earned it all sorts of accolades among sustainable eaters. For a restaurant chain, it has done so much right, including buying more organic and local produce and naturally raised meat. But in the long list of merits, there is a pretty serious stumble that has human rights activists howling.