Make sure when versions that are unavailable do not screw the current/previous versions list

If there are unapproved/unavailable versions for the plugin:
1. If there is another version that links to it as previous, only the name of unapproved/unavailable version should be shown in the Previous versions list
2. If this is a latest version, it should be shown (but only to moderator/cotnributor) above current versions. Version that has no other descendants than unapproved/unavailable versions, should be shown in Current versions list.
3. This way the list of current/previous versions should look the same to people with different view privileges
4. Download latest will download last approved and available version