Update aufs file system support.

Use the default dsgpl source tree, we can't build success with aufs enabled.

So I updated it with the newest aufs source, and make some patch.

Tips: Can not as a module, must built in.

In the Photo Station, aufs can separate original photo files with system generated files, such as thumbs/meta data etc.

Photo source file can restrict it's access privileges, or put it on other share system.