Generate User scaffold.
Validate user attributes.
Be able to use the has_secure_password function.
Make a relationship between user ans project.
Make a user_id attribute accessible.
Make a user test data.
Fix tests.
Add a test user data.
Improve form designs.
Improve a table design of listing users.
TODO: if user doesn't have project, make a create project button.
Add user name column to listing projects table.