Update CHANGELOG from 0.8

https://github.com/rails-api/active_model_serializers/blob/0-8-stable/CHANGELOG.md

Author: bf4

CHANGELOG.md

@@ -241,3 +241,69 @@ Features:
 - [#610](https://github.com/rails-api/active_model_serializers/pull/610) ArraySerializer (@bolshakov)
 - [#607](https://github.com/rails-api/active_model_serializers/pull/607) ruby syntax highlights (@zigomir)
 - [#602](https://github.com/rails-api/active_model_serializers/pull/602) Add DSL for associations (@JordanFaust)
+
+### 0.8.1
+
+* Fix bug whereby a serializer using 'options' would blow up.
+
+### 0.8.0
+
+* Attributes can now have optional types.
+
+* A new DefaultSerializer ensures that POROs behave the same way as ActiveModels.
+
+* If you wish to override ActiveRecord::Base#to_Json, you can now require
+  'active_record/serializer_override'. We don't recommend you do this, but
+  many users do, so we've left it optional.
+
+* Fixed a bug where ActionController wouldn't always have MimeResponds.
+
+* An optinal caching feature allows you to cache JSON & hashes that AMS uses.
+  Adding 'cached true' to your Serializers will turn on this cache.
+
+* URL helpers used inside of Engines now work properly.
+
+* Serializers now can filter attributes with `only` and `except`:
+
+  ```
+  UserSerializer.new(user, only: [:first_name, :last_name])
+  UserSerializer.new(user, except: :first_name)
+  ```
+
+* Basic Mongoid support. We now include our mixins in the right place.
+
+* On Ruby 1.8, we now generate an `id` method that properly serializes `id`
+  columns. See issue #127 for more.
+
+* Add an alias for `scope` method to be the name of the context. By default
+  this is `current_user`. The name is automatically set when using
+  `serialization_scope` in the controller.
+
+* Pass through serialization options (such as `:include`) when a model
+  has no serializer defined.
+
+### 0.7.0
+
+* ```embed_key``` option to allow embedding by attributes other than IDs
+* Fix rendering nil with custom serializer
+* Fix global ```self.root = false```
+* Add support for specifying the serializer for an association as a String
+* Able to specify keys on the attributes method
+* Serializer Reloading via ActiveSupport::DescendantsTracker
+* Reduce double map to once; Fixes datamapper eager loading.
+
+### 0.6.0
+
+* Serialize sets properly
+* Add root option to ArraySerializer
+* Support polymorphic associations
+* Support :each_serializer in ArraySerializer
+* Add `scope` method to easily access the scope in the serializer
+* Fix regression with Rails 3.2.6; add Rails 4 support
+* Allow serialization_scope to be disabled with serialization_scope nil
+* Array serializer should support pure ruby objects besides serializers
+
+### 0.5.0 (May 16, 2012)
+
+* First tagged version
+* Changes generators to always generate an ApplicationSerializer