Veraticus/Dynamoid — pull request #45 by afrojas (2012-05-09 20:40:36+00:00)
Title: Model subclassing support

If you have a 'type' field set, when Dynamoid initializes your model it will create an instance of the class specified in 'type'.
```ruby
class Chamber
include Dynamoid::Document
field :type, :string
end

class ThroneRoom < Chamber
end
```
Now whenever Dynamoid encounters a Chamber object whose type is 'ThroneRoom', a ThroneRoom object is created instead of a Chamber object.