Cache users in leaderboard.
Cache users in leaderboard.

stefanhahmann/pybossa,stefanhahmann/pybossa,geotagx/pybossa,Scifabric/pybossa,OpenNewsLabs/pybossa,jean/pybossa,inteligencia-coletiva-lsd/pybossa,jean/pybossa,inteligencia-coletiva-lsd/pybossa,PyBossa/pybossa,geotagx/pybossa,Scifabric/pybossa,OpenNewsLabs/pybossa,PyBossa/pybossa