apps.core.tests.serialize.feedback: Cleanup.
apps.core.serialize.candidate: Fixed naming.

``candidate`` instead of ``cadidate``.
apps.core.serialize.filemeta: Cache/serializer for Candidate.
apps.core.serialize.filemeta: Import log.
apps.core.serialize.user|candiate: Handle many related objects.
apps.core.serialize.delivery: Cache/serialize Delivery.