Add Micropost model (with tests) and connect to User (with belongs_to/has_many).
Create factory for microposts, add dependency destroy and ordering, validate content.
Show microposts on profile page (includes generating demo microposts).
Implement microposts creation and destruction including access control.
Add proto-feed (microposts to home page near new micropost creation).
Implement micropost destroying.
Finish 'Add user microposts'. Only exercise 6 is solved.