Failed import/rescan of unconfirmed transactions
Created by: LaurentMT
Describe the bug
Imports/rescans fail when trying to import unconfirmed transactions.
Error message is "Column TxnCreated cannot be null"
New method MySqlDbWrapper.addTransactions() introduced by PR #102 doesn't initialize a default value for txnCreated if tx.created is null (see what is done for MySqlDbWrapper.addTransaction())