[#746] Add test guaranteeing we use meta_id and meta_source
[#746] Add test guaranteeing we use meta_id and meta_source

When creating a new record, we use the warehouse's `meta_id` as the new record's
`id` and `meta_source` as its `source_url`. This commit only adds a test to
guarantee that.

Fixes opentrials/opentrials#746
opentrials/processors