Heat the oil in a pan and fry the chicken pieces until golden brown. Remove and reserve chicken. In the same oil, fry the onion and garlic until they start to turn soft. Add the zucchini, tomatoes, oregano and thyme. Continue to fry until some of the sauce has been reduced. Replace the chicken in the pan and season lightly with salt and pepper. Cover and cook over a low heat for approximately 1 hour, stirring occasionally. 10 minutes before the chicken is ready, rinse the olives and add them to the pan. Stir well and cook with the rest of the ingredients. Serve with white rice.