Change log report incorrectly identifying type of entity extended when custom data is changed

Track hours for this task at http://dev.nysenate.gov/issues/7049
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The changelog reports currently retrieve custom data with the assumption that all data sets extend contact records. as a result, changes to non-contact custom data are being linked to contact records as if the entity_id was a FK to contact.id – where it should be an FK to a different object.

We noticed it with relation to a custom data set that extends the address records - but the fix should handle other cases as well.