Fix test failure from earlier test path cleanup
Don't crash when a new attachment is added.
If a model has an existing attachment and styles, and later a new attachment is added (not just new styles), "rake paperclip:refresh:missing_styles" would crash with "TypeError: can't convert nil into Array".
Do not save class instances, save their names.
Saving instances causes memory leaks in development mode in rails.
Tracking new attachment styles with a Rake task to refresh them