JOHANNESBURG( REUTERS)-Shops were looted overnight and a section of the M2 highway was closed in Johannesburg on Sunday( July 11), as sporadic acts of violence following the jailing of former South African president Jacob Zuma spread to the country's main economic hub. Violence had mainly been concentrated in Zuma's home province of KwaZulu-Natal( KZN), where he started serving a 15-month sentence for contempt of court on Wednesday night. Police said criminals were taking advantage of the anger