Added changes from master regarding deletion of previous user avatar
Added changes from master regarding deletion of previous user avatar

OpenNewsLabs/pybossa,proyectos-analizo-info/pybossa-analizo-info,PyBossa/pybossa,inteligencia-coletiva-lsd/pybossa,geotagx/pybossa,jean/pybossa,proyectos-analizo-info/pybossa-analizo-info,harihpr/tweetclickers,Scifabric/pybossa,inteligencia-coletiva-lsd/pybossa,stefanhahmann/pybossa,PyBossa/pybossa,OpenNewsLabs/pybossa,stefanhahmann/pybossa,Scifabric/pybossa,harihpr/tweetclickers,jean/pybossa,proyectos-analizo-info/pybossa-analizo-info,geotagx/pybossa