when a file is downloaded by any browser on Windows the file has no format , how do I solve

[lucaslamounier]

I use the api rest to perform data download : http://localhost:8000/api/estatisticas/subcategorias/?format=csv&uf=&categoria=&subcategoria=&ano=2016 but when the user downloads the file browser for the Windows file comes without the .csv extension

[mjumbewu]

Similar issue to #56. See response there.