Add price fixture
Add FIXES section in TODO
Reorganize TODO, mark unimplemented features
Remove unused import
Add purchases app
Install purchases app
Add purchases.models.Purchase
Add purchases.models.Benefit
Register purchases' models in the Admin
Change Purchase.number to Purchase.amount
Add purchases.views.new_purchase
Add purchase.views.new_purchase_price
Add purchase.views.handle_new_purchases
Add purchases.views.show_purchase