Always update call detail records with the flowsession

https://trello.com/c/qBcdAXy1/1048

Call detail record is now always updated with the flowsession.
Because of this, records from failed calls will also be recorded.
We keep one record per call, which seems the correct approach.

Change-Id: I5000e5a9ae09a2ab78976c2cd7c18c72a4ccf4f4