add Users model
validate presence of name
validate presence of email
validate name length
validate correct email address format
validate email uniqueness
add index to email in User
normalize email address in db
add password digest to User
add has_secure_password
comment out has_secure_password so we can have failing tests initially
test User#authenticate
reenable has_secure_password to finish up password work
silence I18n warning
add Chapter 6 exercises
solve 6.4
solve 6.5
solve 6.6
test for email being saved in all lower case
make test fail temporarily