In Datahub::Factory::Importer, replace ->importer->each with ->each

[pieterdp]

Currently, all importers have the attribute importer, which in itself has the method each. It would be cleaner and more in line with the rest of the application if Datahub::Factory::Importer and children have the method each, so we can replace

$importer->importer->each();

with

$importer->each();

Note that ->each() takes a callback function, so best would be to simply pass-through to the underlying $importer->each() function.