Added deferred exceptions to XAOnePhaseResource

Hi,
I did some changes to fix https://community.jboss.org/thread/235248

I added an interface ExceptionDeferrer that can be implemented by the Resources to save the last error that happened to them. Then I moved the _deferredThrowable variable from TwoPhaseCoordinator up one class into BasicAction. If any excetion occures in BasicAction then BasicAction can ask the resource (if it implements the ExceptionDeferer interface) for the exception and save it in its own _deferredThrowable variable. The TransactionImple class didn't have to be changed. It already asks the transaction for the _deferredThrowable.

What do you think about this solution?
Regards, Sebastian