Additional database field added
Added getPairsForTableByIds() method to Box_Tools
Implemented client_groups for new promo
client_groups functionality added to promo update function
Added empty inputs because otherwise admmin would not be able to unselect all options
Added function to check if Promo is valid for client
Added unit test and updated old ones for isPromoAvailableForClientGroup() method
Integration test added for new promo client group functionality to check if discount is applied correctly