cli: rails g model Relationship follower_id:integer followed_id:integer
*_create_relationships.rb: added 3 indices
*_create_relationships.rb: fixed mistake
schema.rb: cli: rake db:migrate
relationship_spec.rb: added content from Hartl listing 11.2
user_spec.rb: added test from Hartl listing 11.3
user.rb: added :relationships association
relationship_spec.rb: added 4 tests from Hartl listing 11.5
relationship.rb: added associations from Hartl listing 11.6
relationship_spec.rb: added 2 tests from Hartl listing 11.7
relationship.rb: added 2 validations from Hartl listing 11.8
user_spec.rb: added test from Hartl listing 11.9
user.rb: added association from Hartl listing 11.10
user_spec.rb: added 2 tests from Hartl listing 11.11
user.rb: added 'following?', 'follow-bang' methods
user_spec.rb: added 3 tests from Hartl listing 11.13
user.rb: added 'unfollow-bang' method from Hartl listing 11.14
user_spec.rb: added 3 tests from Hartl listing 11.15
user.rb: added 2 associations from Hartl listing 11.16