Add testing-specific methods to ProvenanceStorageInterface
Refactor provenance_heuristics test so that it doesn't perform direct SQL queries,
hence being able to test different backends in the future.
Add parametrize batch option to heuristics test
Add RevisionData and RelationData to improve ProvenanceStorageInterface
Get read of Tuples in favour of more declarative objects for passing data.
Update the usage of the involved methods as well.