Modify fileconn.dir.photos property

Some MIDlets assume that the fileconn.dir.photos property is either null or "file:///" + SOMETHING + "/".
We could set it to null and avoid creating the "Photos" directory at startup, but I think in the future we could make "Photos" a mount point with a FS implemented with Device Storage and thus save the photos in the Firefox OS gallery.
Why not just check that it's the exact value we expect? Or if that isn't a good idea for some reason, then why not just check that `photoDir.length() > 8`?