Generate Relationship model per listing 11.1.
Reset database.
Test relationships per listings 11.2 and 11.3.
Add association per listing 11.4.
Test belongs_to association per listing 11.5.
Add associations per listing 11.6.
Test validations per listing 11.7.
Add validations per listing 11.8.
Test for :followed_users attribute per listing 11.9.
Add association to :followed_users per listing 11.10.
Add tests per listing 11.11.
Add #following? and #follow! per listing 11.12.
Add test for #unfollow! per listing 11.13.
Define #unfollow! per listing 11.14.
Test for reverse relationships per listing 11.15.
Add reverse relationships per listing 11.16.
Modify 'populate' task to create relationships per listing 11.17.
Add 'following' and 'follower' routes per listing 11.18.
Test stats per listing 11.19.
Add stats partial per listing 11.20.