Migrate importer tests to the new tests infrastructure

Migrated all tests to the new test infrastructure, shaving another minute and 15 seconds from the overall test time for importer (down to 1m46s on my machine)

Now.. not 100% sure how to run the Oracle and SQL tests, so it's rather likely I've not done that migration right. Justin/Ian, can you help?
Do you prefer to take over the pull request, or me to commit and follow up with fixes for those two tests?