HAVANA, June 23, 2016 (Xinhua) — Image taken on June 23, 2016 provided by the Venezuelan Presidency shows the United Nations Secretary-General Ban Ki-moon (L) shaking hands with Venezuelan President Nicolas Maduro prior to the signing ceremony of a histo HAVANA, June 23, 2016 (Xinhua) -- Image taken on June 23, 2016 provided by the Venezuelan Presidency shows the United Nations Secretary-General Ban Ki-moon (L) shaking hands with Venezuelan President Nicolas Maduro prior to the signing ceremony of a histo