3771 Tag Sets without visible tag lists are hidden

If you didn't select "Visible tag list?" on a tag set, your tag _set_ wasn't showing up anywhere (index, search) because of some confusion in the controller. The controller was using `visible` as if it referred to the visibility of the tag set itself, but it actually refers to the "Visible tag list?" setting and therefore the visibility of the tags within a given tag set.

https://code.google.com/p/otwarchive/issues/detail?id=3771