Simplified default surefire configuration
Reworkded Transaction tests in order to factorize the Bitronix setup.
Allow the TransactionService to be part of an already opened transaction.
Refactoring with TransactionServiceContext

Add a TransactionServiceContext to track the reentrant calls and the flag to know if
the transaction boundaries are managed externally.
Remove and fix the @Ignore for the monitoring of active transactions.
Transaction synchronizations

- Register the transaction's synchronizations in both cases : we manage it or not.
- Simplified the usage of the ThreadLocal
Fixed Javadoc to avoid importing SystemException from Corba package.
Extract interface UserTransactionService

- Extract the interface UserTransactionService to allow only the 2 methods executeInTransaction and registerBonitaSynchronization
- Replace getTransactionService with getUserTransactionService
- which implies to use executeInTransaction to manage the transaction stuff
- Refactor CommandAPIImpl
Added the method executeWithUserTransactions in CommandAPI

This method will allow the user to define any transactions in a
command implementation.