Added the user profile feature with controller and model test specs.
Fow displaying People I Follow page. Added the follows table, model, controller and test specs. Make follows associate with users.
Added more default users and following relationship in seeds.
Added the unfollow feature.
Changed follow to followship.
Refactored by the solution video.
Added two index to followships.
Fix a bug, rename user to leader.
Added the follow feature with model, controller and feature test specs.
Refactored by the solution video.
Removed useless foreign_keys.
Merge pull request #7 from HenrykChiu/week_4_code_review_1

Week 4 code review 1