removed controller for users, roles and comments
[Category] add validations to page_title and keyword
added controller macros
added flash message in admin
[Layout] fix typo of class suggestion
[Admin::CategoriesController] added
[Admin::BaseController] fix tests
added default_scope to contact
[Admin] refactoring to use meta_tag partial
removed deprecations warnings
removed show actions that is not used
[PostsController] fixed tests
removed old tests of admin controllers