BUENOS AIRES (Reuters Life!) - On the fourth floor of Buenos Aires’ largest psychiatric hospital, patients dance the tango with doctors and nurses. A few months ago some were too shy to talk and others could barely keep their balance when they walked. Today, they embrace their partners cheek-to-cheek, gliding and pausing across the floor to the mournful chords of a traditional accordion. Doctors as far afield as Italy and Australia are using Argentina’s world famous tango to