Add User model
Migrate the database
Prepare test dile for User model
Add presence validations for User name and email attributes
Add length validation for User name attribute
Add syntax validation for User email attribute
Add uniqueness validation for User email attribute
Add uniqueness index to the email attribute of the User model
Add the before_save callback to make sure all email attributes for Users are totally lowercase before being saved to the database
Add bcrypt-ruby gem to Gemfile
Update Gemfile.lock
Add bcrypt-ruby gem to Gemfile
Add password_digest and has_secure_password attributest to the User model
User has a secure password