[-] BO: Fix undefined feature value when importing products with inactive lang

Feature value should inherit from the imported value for any languages, even if they are disabled.
Example: if default language is disabled and you try to import a product with a feature, import will fail because value is empty.

Anyway, excluding this case, we really think that value should always be filled even if the lang is inactive at this time.
Merge pull request #2331 from prestamodule/patch-7

[-] BO: Fix undefined feature value when importing products with inactiv...