To avoid us having to construct the URL for public shares just rely on the
server to do it.
This makes it easier to maintain. For example if (in the not do distat future)
the index.php part is removed the server would just server this new url.
If we have a slow connection we do now want to show the share checkbox until we
have retrieved the shares (so we know the state). Else we might try to enable
sharing on an already shared file.
Roeland Jago Douma