With temperatures so dangerously low that courts closed for two days, the city of Chicago wasn’t waiting around for a judge’s order to crack down on landlords violating the heat ordinance.On Wednesday, Mayor Rahm Emanuel announced he directed the city Department of Buildings to use its “full police power” to appoint receivers who can restore heat and hot water to the required levels under city code.The city’s Law Department said the city took the action against at least seven residential …