Added transaction support to Dalapi's DataCommon class

// open a transaction
using (DataCommon.DalapiTransaction transaction = new
DataCommon.DalapiTransaction())
{
try
{
// add some data
TestingTableDO first = new TestingTableDO() { ExpectedDueDate =
DateTime.Now.AddDays(5), Id = 1, Name = "First", SystemName = "Primary
System" };
TestingTable.Create(first);
Console.WriteLine("Added a record");

// commit the transaction
transaction.CommitTransaction();
Console.WriteLine("Committed");
}
catch (Exception ex)
{
// rollback the transaction
transaction.RollbackTransaction();
Console.WriteLine("Rolled back");
}
}