How to do an action in a contract to transfer tokens to other user accounts without adding permission?
Actually, in dawn3.0 i can use the function like this below,
but in dawn 4.0 it doesn't work

            action(
                permission_level{ lender, N(active) },
                N(eosio.eos), N(transfer),
                std::make_tuple(lender, _self, shouldback,std::string(""))
            ).send();