The new owner of Mainescape, a longtime garden center in Blue Hill, wants to add beer service from his brewery this year as he expands production. He might one day create an onsite taproom on the property, he said. Spencer Janney, owner of Naiad Country Brewery in Orland, bought the center from founder Don Paine and his wife, Althea, in February. He’s continuing to run the garden center as it has been, a resource he said he’s committed to mainta…