generate micropost model
add spec for user_id validation on micropost and add validation
add associations between microposts and users and specs
add test for user responding to #microposts
add micropost factory
add test spec ordering microposts by created_at
add default_scope to micropost model in order the microposts by created_at
microposts now get deleted when their associated user is deleted
add validations for micropost content presence and length
add markup for listing microposts and specs
add micropost partial and @microposts instance variable to users controller
add sample microposts to rake task
fix bootstrap columns
add styling for microposts
add micropost routes
move signed_in_user method to sessions helper to be used in microposts controller
add create action to microposts controller
add partials for home page
fix partials
fix columns