In a large bowl, mix together the cake mix, melted butter, and eggs. Stir in the oats, brown sugar, ginger and cinnamon. Set aside about 1 1/2 cups of the mixture, and spread the rest into the bottom of a 9x13 inch baking dish. Pack down to form a solid crust, getting it as even as possible. Spread the cooled cranberry mixture over the crust. Pinch off pieces of the remaining mixture and place evenly over the cranberry layer.