Kansas City’s Trozzolo Communications Group is adding 12 high-end jobs and investing $400,000 into its downtown headquarters. Trozzolo bought the historic Nelkin-Piper Building back in 2010, and was one of the first companies to be a part of the rejuvenation of the area. “Trozzolo’s investment is strengthening Kansas City’s economy as well as the heart and soul of its downtown,” said Mike Downing, director of the Missouri Department of Economic…