BALTIMORE — A Baltimore officer was acquitted of assault and other charges today in the arrest of Freddie Gray, dealing prosecutors a second straight blow in their bid to hold police accountable for the black man’s death from spinal injuries suffered in the back of a police van.The judge who decided officer Edward Nero’s fate in the non-jury trial concluded Nero played little role in the arrest and wasn’t responsible for the failure by police to buckle Gray in during the jolting ride.Upon hearing …