Downtown club uses clever cocktails, and new technology, to make Champagne available to the masses by Hal B. Klein "Everyone thinks that champagne is just for celebratory reasons — unless you're of the upper echelon," says Peter M. Landis, managing partner of Perlé, a champagne-and-tapas lounge in Downtown's Market Square. Indeed, a quick glance at Perlé's extensive menu of bubbly may well seem …