Move associations to Seller and Buyer accounts.
Use FactoryGirl properly.
Apply new factories in setup for registration step two spec.
Apply new factories in spec setup for registration step three.
Apply new factories in spec setup for step four in registration.
Tidied up user model with new associations and factories.
Improve debtor integration spec and use a CompanyProfile Facade.
Improve invoice integration spec.
Test delegators are in fact delegating to company.
Rename AuctionBuilder to AuctionFactory.

* Assign company_id from user when building record.
Clean up Seller creates Auction spec.
Clean up seller sees auction spec.
Clean up company profile specs.
Clean up auction specs.
Clean up buyer bid spec.
Clean up seller selects winning bid spec.
Make specs pass for registration step two.
Refactor session redirector specs.
Fix step four registration spec.
Seller signs in spec.