Pound chicken breasts to a uniform 1 inch thickness. Cut each breast into two equal parts. Combine marinade ingredients together in a nonreactive bowl or resealable bag. Add chicken pieces and set aside for one hour. Remove chicken from marinade, drain and coat with chopped rosemary. Set aside for about 30 minutes. Preheat grill. Meanwhile combine mayonnaise, capers and olive oil. Mix well. Place chicken pieces on grill and cook for about 5 to 6 minutes per side or until done. Remove from grill and assemble into sandwiches with dressing on top.