Merge branch 'master' into changelogs-for-ideas-comments-and-articles

* master:
  Remove extra columns from changeloggable_items table.
  Fixed views to show deleted changeloggables and unknown changers.
  Show changer in changelog list.
  Save changer to changelogs.
  Specs for Changelogger module.
  Specs to test successful index actions for admin controllers.
  Show AR models' changelogs in admin.
  Require Differ.
  Default scope and pagination per_page method for Changelog model.
  We need also changer for changelogs.
  Include Changelogger to Idea, Comment and Article.
  A Changelogger module to be included into models.
  Created Changelog model.

Conflicts:
	spec/modules/changelogger_spec.rb