Create User model
First test for User model
Add tests for valid emails
Add validation for email validity
Add test for email uniqueness
Enusre uniqueness of user email in model
Modify email uniqueness test for case insensitivity
Modify model validation for case insensitive emails
Ensure email uniqueness in database as well
Ensure that all emails are saved in lower case
Install bcrypt gem
Add test for pasword digest to user model tests
Add pasword_digest to Users table
Add pasword_digest to Users table
Add tests for password and password confirmation
Add tests for password and password confirmation
Add tests for password and password confirmation
Add has_secure_password to users model
Add tests for password length and user authentication
Add validation for password length