SAIGON, April 30, 1975 (UPI) -A triumphant Communist army riding tanks, trucks and captured American Jeeps took over Saigon Wednesday and raised the Viet Cong flag over the presidential palace. The Communist world hailed it as a great victory of historic The Viet Cong and North Vietnamese troops-jubilant over the unconditional surrender that ended 35 years of war against American, French, Japanese and South Vietnamese forces-seized Saigon Radio and announced that they have renamed the South