Add support in windows for getting a list of disks and stats about each (#11)
Add support in windows for getting a list of disks and stats about each (#11)

The implementation is basic. It exports only few info:
- Getting a list of disks returns only the name and the type.
- For each disk, total, free, available, used disk space is returned

knz/gosigar,eonarheim/gosigar,elastic/gosigar