added changes needed for running script on OSX

This is the modified script for downloading all data files into macintosh. The following changes were needed:

1) Set system locale to Portuguese
2) Set encoding to Windows
3) OSX uses a different 7-zip application
4) OSX needs you to specify a path to perl when using read.xls
5) OSX needs you to specify a path to unzip application
6) I had to add some folders to the paths leading to the extracted files
7) OS is case sensitive: curfile stem needs and extension need to be in the right case