(owners were not required to obtain a building permit to build a horse barn because it qualified as an “agricultural building,” entitled to an exemption under township’s uniform construction code; the planned horse born, including stables for horses and a riding ring to exercise the horses, was not open to the general public, but accessible only to invited guests; a building could be both an “agricultural building” and a “commercial building”; the court also found that horses, regardless of their use, constituted “livestock”).