Make a pocket in each chicken breast half by cutting horizontally from one side almost to the opposite side. Place chicken in a re-sealable plastic bag set in a shallow dish. For marinade: In a small bowl, combine mustard, mayonnaise, oil, vinegar, oregano, basil, and rosemary. Pour over chicken. Seal bag; turn to coat chicken. Marinate in the refrigerator for 2 to 4 hours, turning bag occasionally. Remove chicken from marinade, scraping off and discarding excess marinade.