CARACAS, Venezuela, Aug 28 (Reuters) - Venezuelan President Hugo Chavez said on Sunday his government would take legal action against Pat Robertson and potentially seek his extradition after the U.S. evangelist called for Washington to assassinate the South American leader. Robertson, who later apologized for the remark, said he was expressing his frustration with Chavez's constant accusations against the administration of President George W. Bush. "I announce that my government is going to take legal action in the United States ... to call for the assassination of a head of state is an act of terrorism." Chavez said in a...