2015087174 - Improved import / export of goods from Opencart

- for the action “Import products from Opencart”, the checkbox “Import only products that have changed to opencart since the last import by the action” has been improved; - for the action “Upload products/categories/filters/characteristics to opencart (via DB)”, the ability to transfer the date of the last product changes to OneBox has been improved; - for the action “Upload products/categories/filters/characteristics to opencart (via database)”, the setting "Upload only products that have been updated in the last specified number of hours" has been improved.