Add more globla stats.
Add more globla stats.

This commit adds the number of published apps on each categorie as part of the
JSON object with stats.

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