Closes#1977, Refs #3473
- Ensure that import operations are run in sequence.
Previously the operations were started in order but subsequent
ops were allowed to begin before the previous finished, which would
result in out-of-order execution.
- Fix bug in attach() where a model property was being passed in
instead of a transaction object. If the call was made when a
transaction was in process, it could cause bookshelf/knex to
hang and never finish the transaction.