Enrich Task event listeners data

The customer ask us for making some enhancements in the event listeners after testing the improvements we've done in BAPL-674

• As the rest of task events, in the case of AddedTask, the event date created in every event has to be the same we store in the table AUDITTASKIMPL. Currently, we are store a "new date", so both data are different between each other.
• The first time the event beforeUpdateOutputVariableChange is fired, the value of the variables is the new variable instead of "null". The would like to get the real current value.