Add Installment#actionable
Add Installment#actionable

This scope returns all installments which have not been fulfilled by a
Spree order and the actionable date is today or has past.

It is used to find installments that require reprocessing

solidusio-contrib/solidus_subscriptions,solidusio-contrib/solidus_subscriptions,solidusio-contrib/solidus_subscriptions,solidusio-contrib/solidus_subscriptions