Create a script adding "Countries where sold" to products as prices are added

[teolemon]

Problem

• Create a script adding "Countries where sold" to products as prices are added
• This requires
• deducing the country from the associated stores
• checking whether the product already has this country in "Countries where sold"
• if not adding it.

Why

• We currently add countries yearly using scan statistics
• Prices allow us doing that in almost real time, much more aggressively and reliably than scan statistics