Revert "Rails 3.0.x fails to load helpers in Engines (?)"

This reverts commit 00c912d12b.

reason: reverting back from app/helpers to ActionView::Base freedom-patch.
Because mounted engines on the app doesn't search the main_app's helpers, then throws "undefined method `paginate'" in the views

lib/kaminari/hooks.rb

@@ -27,14 +27,6 @@ module Kaminari
         ::MongoMapper::Document.send :include, Kaminari::MongoMapperExtension::Document
         ::Plucky::Query.send :include, Kaminari::PluckyCriteriaMethods
       end
-
-      # Rails 3.0.x fails to load helpers in Engines (?)
-      if defined?(::ActionView) && ::ActionPack::VERSION::STRING < '3.1'
-        ActiveSupport.on_load(:action_view) do
-          require 'kaminari/helpers/action_view_extension'
-          ::ActionView::Base.send :include, Kaminari::ActionViewExtension
-        end
-      end
       require 'kaminari/models/array_extension'
     end
   end