Add tests to verify db version hasn't changed

issue #4479

- these tests will need updating if ever the db schema (not inc validations), permissions fixtures or db
version ever changes
- the intention is that it is no longer possible to accidentally change permissions or the db schema without
knowing you need to update the db version and the values in this test file
Merge pull request #4688 from ErisDS/migrate-test

Add tests to verify db version hasn't changed