Move /cards route under /board/1
Associate cards directly to boards

...via has_many through relationship
Add :show route for cards
Create comments table

* Add Comment partial
Delegate :board to Card#list
Make a real User model available through controller #current_user
Add comment creation form
Add I18n for comment creation error
Make cards clickable (e.g. link_to card :wink:)
Latest comments should stick at the top
Merge pull request #15 from task-planner/comments