MADRID, May 25 : "Twenty-five years on, Europe will see us again," read the banner at Rayo Vallecano's tiny, concrete cauldron a year ago, as fans poured on to the pitch at the Estadio de Vallecas to celebrate the club's return to continental football. What even the most romantic believers at this working-class club on the outskirts of Madrid might not have imagined was that 12 months later, Rayo are preparing for their first European final. They face Premier League side Crystal Palace in the