Support for setxattr and statfs, unicode filenames

Support for setxattr and statfs implementation so that Finder is able to copy files to fuse mount (free disk space).

Output of df -h:

```
node@fuse0     1.2Ti    0Bi  1.2Ti     0%         0 10000000    0% PATH
```

And I changed all String::AsciiValue calls to String::Utf8Value for unicode support.