WASHINGTON - Walmart (WMT) has pulled a T-shirt offered by an outside seller from its online store after a journalist advocacy group told the retailer it found the shirt threatening. The shirt, listed on Walmart.com through third-party seller Teespring, said: "Rope. Tree. Journalist. SOME ASSEMBLY REQUIRED." "This item was sold by a third-party seller on our marketplace and clearly violates our policy," Walmart said. "We removed it as soon as it was brought to our attention, and are conducting a thorough review of the seller's assortment."Teespring, which is owned by KA Design, allows people to post shirt designs. The company...