Marketplace: Bill Radke: Oil dependent countries are quaking as the price of a barrel of crude drops and drops. This morning, OPEC oil ministers meeting in Vienna agreed on a big production cut — 1.5 million barrels a day starting next month. But oil is still trading below $63 a barrel this morning compared to $147 this summer. That might sound great as you watch the price of gas fall below three bucks, but as Sarah Gardner reports from the Marketplace Sustainability Desk, as oil goes, so goes renewable …