Auto fill private checkbox
If you are adding to a private folder, the 'private' checkbox in both the folder and file forms is by default checked. Because folders/files don't inherit the privacy settings of their parents. Also fixed bug where files in database that don't exist in file system couldn't be deleted.
Hide Private Folders
Made private folders invisible to non admins, any access to them results in an flash message error. TODO probably make files public only again. Because they need to be downloadable to anyone with a link.
Remove private files
Private files didn't really have a point because they needed to be left downloadable by anyone. So removed options to make them private