CAPX-58: Added validation to importer.

CAPX-58: Added validation to importer.

How to test:
* Create new content type
* Create new mapper with this content type
* Create 2+ importers with this mapper, do not import
* Remove content type created in the first step
* Click "Update profiles now" on importers page

Please change to:

$message_text = t('Invalid bundle setting on %mapper. The bundle %bundle is no longer available and should either be restored, or the mapper %mapper should be deleted.');