In a down-and-out Canadian town, Bruce Linton dreamed of transforming an abandoned Hershey Co. chocolate plant into the Next Big Thing, a medical marijuana factory. But the pot entrepreneur faced a crisis typical of his edgy industry: Banks shut their doors in his face. Then Linton turned to an old-school credit union - that paragon of community, rectitude, and caution - and found a middle-aged banker named Rob Paterson. The chief executive officer of Alterna Savings & Credit Union Ltd. seemed an unlikely mark. He barely drank and hadn’t smoked a joint since his university days.