Updated Guardfile.
Test and generate Microposts with a user_id, created_at index.
Create a User has many Microposts relationship.
Make the User has many Microposts relationship dependent on the existence of a user.
Add validation to Micropost fields.
Add microposts to User profile.
Create sample microposts and add CSS for microposts.
Limit Microposts to create and destroy methods only.
Add forms for creating Microposts.  Refactor errorsr into shared partial.