In the southern half of the state, it might seem that you can’t swing a dead cat without hitting a craft brewery. But in the northern half, Maine’s brewing phenomenon has been slower to take hold — though some people are starting to change that. Joel and Jona Fitzpatrick last week opened their years-in-the-making brewery and taproom, Katahdin Brew Works, in the Penobscot County town of Patten, right on the Aroostook County line.