NEW YORK (Reuters) - The United States should give the United Nations until the end of the year to reform and then consider cutting back on its U.N. dues if the changes fall short, U.S. Ambassador John Bolton said on Monday. "Is good management and lack of corruption too much to ask for?" he asked, calling the United Nations "severely challenged from a management and accountability point of view." Bolton made his comments in response to a question after addressing a symposium on the future of the United Nations sponsored by the conservative Hudson Institute. The United States, one of...