model_name is not a String

The weird errors were from Rails not knowing how to generate routes. We were trying to feed it "skin" as the model_name for WorkSkin, but model_name is not a String, it's an ActiveModel::Name.

http://code.google.com/p/otwarchive/issues/detail?id=3679
http://code.google.com/p/otwarchive/issues/detail?id=3680