Add Micropost model and associations with User
Add a factory for Microposts with an association to user
Annotate Microposts db columns
Put the microposts in descending order (newest to oldest)
Ensure that users microposts are destroyed along with the user (dependent: destroy)
Add Micropost content validation (presence and no longer than 140 characters)
Display user's microposts in user show page
Add partial for micropost in user show page, add a paginate, and a task to populate the user's microposts
Add style to microposts
Move signed_in_user method to sessions helper
Access control to microposts create and destroy actions
Make error messages partial generic
Create micropost with valid and invalid information
User respond to feed method
Microposts feed
Refactor views with partials
Destroy micropost action