Farm workers of Hacienda Luisita are challenging President Gloria Macapagal-Arroyo to prove that she is not merely using the Hacienda Luisita issue to spite former Pres. Corazon Cojuangco-Aquino, heir to the Luisita estate and one of the president’s main political opponents. BY DABET CASTAÑEDA Bulatlat.com Farm workers of Hacienda Luisita, the 6,419-hectare sugar estate owned…