protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
ProductMap.Map(modelBuilder.Entity <Product>());
ServiceMap.Map(modelBuilder.Entity <Service>());
TransactionMap.Map(modelBuilder.Entity <Transaction>());
ItemTransactionMap.Map(modelBuilder.Entity <ItemTransaction>());
ItemTransactionChargeMap.Map(modelBuilder.Entity <ItemTransactionCharge>());
}