LONDON–**For Olivia Matabata, 2007 was a devastating year.     Her middle son was sick at home with AIDS, and Ms. Matabata, who has five grandchildren, was desperate for information on how to help him.    A neighbor encouraged her to attend a four-day workshop at Grandmothers Against Poverty and AIDS (GAPA), a local community and education center in the Khayelitsha Township near Cape Town. Read more