* U.N. teams found cluster bomb remnants
* Widely-banned explosives can kill and maim civilians
* Warring sides accuse each the other of massacres
By Carl Odera
JUBA, Feb 17 (Reuters) - South Sudan's army on Monday denied using cluster bombs in its fight with rebels, shrugging off a U.N. report that fragments of the widely-banned explosives had been found.
Weeks of fighting ...