relax Kaminari requirement as per amatsuda/kaminari#481
Ensure undecorated resource type for AA:Comments

Comments form were being generated from decorated resource, it breaks
AA::Comments. This patch acts on AA::Comment.resource_type that is
being used to populate resource_type hidden input in comments' form

- Add support to ActiveSupport < 4
- Remove unneeded expectation option [ci skip]