(Reuters) - Volunteer watchman George Zimmerman suffered "insignificant" injuries in the fight in which he shot and killed unarmed black teenager Trayvon Martin, a medical examiner testified on Tuesday, as prosecutors attempted to undermine Zimmerman's claim he feared for his life. Testifying for the prosecution at Zimmerman's trial, Medical Examiner Valerie Rao said she reviewed Zimmerman's medical records and 36 pictures of his injuries taken at the police station after the fight. "They were not life-threatening. They were very insignificant," Rao told the Seminole County criminal court jury. Zimmerman, 29, has said Martin, 17, punched him in the face and...