Finished first-draft implementation

app/assets/stylesheets/posts.scss

app/controllers/articles_controller.rb

app/controllers/posts_controller.rb

app/controllers/questions_controller.rb

app/helpers/application_helper.rb

app/helpers/post_types_helper.rb

app/models/article.rb

app/models/post.rb

app/views/articles/_form.html.erb

app/views/articles/edit.html.erb

app/views/posts/_article_list.html.erb

app/views/posts/_expanded.html.erb

app/views/posts/_form.html.erb

app/views/posts/_list.html.erb

app/views/posts/new.html.erb

app/views/questions/tagged.html.erb

config/routes.rb

test/controllers/articles_controller_test.rb

test/controllers/moderator_controller_test.rb

test/controllers/questions_controller_test.rb