LAS VEGAS — For the third consecutive year, the National Rugby League is kicking off its season with a doubleheader at Allegiant Field.  Each year, the NRL has brought four new clubs to Las Vegas to showcase the game.  This year, the Queensland Cowboys play the Newcastle Knights in a 9:15 p.m. ET game Saturday that will be followed by the Canterbury Bulldogs playing the St. George Illawarra Dragons at 11:30 p.m.  Of the four teams, the Bulldogs appear to be the most elite side based on last