Use an options hash for ItemCombinable.add_or_update instead of default values
Use Ownership.add_or_update in OnlineFulfillment#process_fulfillment!
Use Ownership.add_or_update in ShippingFulfillment#process_fulfillment!
Make associations more consistent for factories
Add Shipment factory
Add Ownership factory
Add more specs to Shipment specs
Add more specs to Ownership specs
Fix style -- rubocop