Wrap factory_girl linter in a transaction.
Wrap factory_girl linter in a transaction.

Since https://github.com/thoughtbot/factory_girl/pull/707 the linter now
calls create on each factory, and this was polluting the database.
Wrapping this in a transaction that's rolled back prevents this.

alphagov/content-register,alphagov/content-register,alphagov/content-register