BOSTON (Reuters) - Former President Bill Clinton said on Wednesday Congress should change the rule that barred him from seeking a third term in the White House, but stopped short of saying he wants to return as commander-in-chief. Speaking at the John F. Kennedy Library and Museum here, Clinton questioned certain aspects of the 22nd Amendment of the U.S. Constitution, which prevents a person from being elected president more than twice. Clinton said the amendment, passed after Franklin D. Roosevelt was elected to a record fourth term, should be changed simply to keep a person from being elected to more...