Rails: 4.0.3
Mongoid: 4.0.0.beta1
mongoid-paperclip: 0.0.8

Can't upload file with paperclip get, I get an error

`NoMethodError (undefined method 'after_commit' for Draft:Class):
app/models/draft.rb:5:in '<class:Draft>'
app/models/draft.rb:1:in '<top (required)>'
app/controllers/drafts_controller.rb:27:in 'create'`

`class Draft
include Mongoid::Document
include Mongoid::Paperclip

has_mongoid_attached_file :image,
:path => ':attachment/:id/:style.:extension',
:storage => :s3,
:s3_credentials => File.join(Rails.root, 'config', 'aws.yml'),
:styles => {
:small => ['298x160#', :png]
}
end`