Updated to latest Rails 3.2.13.rc2 and Mongoid 3.0.23

Having a problem with a Mongoid::Fields::Serializable. Seems it was removed after 3.0 series. I would lke to go over this project a bit with you to figure out how to solve this issue. Here's the exact error stack trace:

```
ActionController::RoutingError (uninitialized constant Mongoid::Fields::Serializable):
  app/models/inc_date.rb:4:in `<class:IncDate>'
  app/models/inc_date.rb:3:in `<top (required)>'
  app/models/artist.rb:12:in `<class:Artist>'
  app/models/artist.rb:1:in `<top (required)>'
  app/controllers/artists_controller.rb:1:in `<top (required)>'
```