little refactoring of unit tests, new test test_csv_headers_are_correct
little refactoring of unit tests, new test test_csv_headers_are_correct


Former-commit-id: c38d7d15b9d0c8e5578b39427074a30208a18baf [formerly c38d7d15b9d0c8e5578b39427074a30208a18baf [formerly edc3e58a4f1047ea4c5307019c234d54f5be0605]]
Former-commit-id: 3925dcc814858079a0d28731f9d9dd92e664a672
Former-commit-id: 0d0e451ffff4bc97688c38742a16067e6ad63e10
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine