* Move all features to system * Remove database_cleaner & apply use_transactional_fixtures * Move rspec-retry to :test * Update Capybara config * Update rails_helper * Fix user_visits_a_comments_page_spec.rb * Fix lint
* Reduce the number of sql queries for articles comments * Refactor comments tree display * Refactor retrieving the comments tree * Remove comments tree view object * Update score in comments spec for consistent order