Some clients like FileZilla need 'longname' attributes to read directories properly

[uberbrady]

Great notes here: https://github.com/BriteVerify/node-sftp-server/issues/42

But, basically, you need the long-listing attribute to be set right to read a directory. The best fix will be to dynamically generate the longname attribute based on the mode, file type, name, file size, username, and group of the file.

But if we can't do that, we should at least document that this is how you should build longname attrib's.