Fix dir paths for MEDIA_LIBRARY_PER_SITE.
Fix dir paths for MEDIA_LIBRARY_PER_SITE.

ryneeverett/filebrowser-safe,ryneeverett/filebrowser-safe,ryneeverett/filebrowser-safe,fawx/filebrowser-safe,ryneeverett/filebrowser-safe,fawx/filebrowser-safe,fawx/filebrowser-safe