Wanted: Middleweight martial artist willing to step into cage in front of loud group of soldiers at Kentucky military installation, fight Texas National Guardsman who served in Iraq and Afghanistan and hasn’t been knocked out in 20 professional bouts. Experience a plus. Medical insurance probably also a good idea. Tim Kennedy had been set to headline “UFC Fight Night 31: UFC Fight For the Troops 3” at Fort Campbell, Ky., on Nov. 6 against Lyoto Machida, a former 205-pound champion set to drop to 185 pounds in what would be the biggest fight of Kennedy’s career. But late last week,…