Add helper to filter documents on :part_of_taxonomy_tree in rummager tests
Add helper to filter documents on :part_of_taxonomy_tree in rummager tests

Whitehall::NotQuiteAsFakeSearch acts as a fake for Rummager access
in some of the tests. However, searches on the field 'part_of_taxonomy_tree'
will not work without adding the parameter explicitly to the data store

alphagov/whitehall,alphagov/whitehall,alphagov/whitehall,alphagov/whitehall