A group of Iowa City restaurant owners have joined forces to take on GrubHub for food delivery dominance in the city.Nineteen owners that run 24 restaurants in the college town launched Chomp in early November as an alternative to GrubHub. Both GrubHub and Chomp are online services that let customers order food from local restaurants and have it delivered directly to them.Founders of Chomp said they came together after GrubHub acquired the Iowa City food delivery market from OrderUp earlier this year.