By Cathy Horyn January 20, 2011 3:45 pm January 20, 2011 3:45 pm Valerio Mezzanotti for The New York Times The runway at the Rick Owens show in Paris. Louis Vuitton will open a new store in Place Vendôme sometime soon. That made me breathe a sigh of relief. Its latest men’s collection, designed by Paul Helbers and shown at the start of the Paris fall collections this week, may look austerity-minde