Updating CHANGELOG for 1.2.1
Updating version for 1.2.1
Adds 'decorator_class?' method

Indicates whether a class can be decorated or not without resorting to a
rescue in application-level code.
Merge pull request #539 from pmcneill/is_decoratable

Add `decorator_class?` method to Decoratable
Fix Rails 4.0 tests
Use AM::Serializers 0.7 on Rails 3.0

Due to rails-api/active_model_serializers#304
Clear ViewContext before specs instead of after

By doing it before, we get sure that another type of spec (model,
acceptance) does not leave ViewContext in a wrong context...

https://github.com/drapergem/draper/issues/523
Merge pull request #547 from gaizka/master

Clear ViewContext before specs instead of after
Alias `object` to `#{model_name}`

If we have an `ArticleDecorator` there is going to be a method
added to it named `article` which is convenient for the user.
Require NameError#missing_name? from ActiveSupport
Improve aliasing to object class name
Only define MongoidPostDecorator when using Mongoid
Merge pull request #541 from haines/object_class_name_alias

Alias `object` to `#{object_class.name}`
Make CONTRIBUTING.md slightly friendlier

Make CONTRIBUTING.md that little bit friendly by saying thanks at the top, and linking to issue reports new issue pages.
Merge pull request #552 from iHiD/patch-1

Make CONTRIBUTING.md slightly friendlier