protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.Configurations.Add<Customer>(new CustomerMapping());
modelBuilder.Configurations.Add<Product>(new ProductMapping());
modelBuilder.Configurations.Add<Category>(new CategoryMapping());
modelBuilder.Configurations.Add<Order>(new OrderMapping());
modelBuilder.Configurations.Add<OrderLine>(new OrderLineMapping());
}