Update carrierwave

#{column}_identifier must be used to get the name of the file

Gemfile

@@ -3,14 +3,15 @@ gem 'rails'
 gem 'yajl-ruby', :require => 'yajl'
 
 gem 'bson_ext'
-gem 'carrierwave', '0.5.4'
+gem 'carrierwave'
+gem 'carrierwave-mongoid', :require => 'carrierwave/mongoid'
 gem 'ckeditor'
 gem 'devise'
 gem 'mini_magick'
 gem 'rubyzip'
 gem 'sinatra'
 gem 'execjs'
-gem 'mongoid', :git => 'git://github.com/mongoid/mongoid.git', :ref => '7a915395db50e2bc6071a503a11530e644879e49'
+gem 'mongoid'
 
 gem 'rake'
 gem 'jquery-rails'