Add revenue by date
Add most_items
Add inspect to repositories
Add most_items
Fix Merchant#invoice_items, add most_items to merchant_repository
Fix merge conflicts
Fix revenue by date
Add pending invoices
Fix merge conflicts
Add most_revenue to item repository.
Update most_items
Fix merge conflicts
Update most_items - first working solution
Refactor and cleanup
Refactor merchant
Final cleanup before attacking invoice creation