Add validations to AR

Refactor filters module to use AS::Concern

Implement view rendering.

Implement after_action

Implement before_action

Refactor rendering logic

Implement Rack Application

Implement a simple Rack app

Implement User.all

Implement ActiveRecord

Add more code for rendering exercise.

Remove config/routes.rb

Update to Rails 4.2

Update Rails to 4.1.6. And add boot.rb file.

Update to Rails 4.0.4