update gems
fix indentation
validates presence of username
change routes
change form url
a nicer error message
uniqueness is no more sensitive to the case
install bcrypt-ruby
add password digest to users (and remove password and password_confirmation)
add has_secure_password
create title helper
display title in layout
add title for signup page
add title for profile page
generate sessions controller
custom routes for login
sessions new
session create
logout path
add current_user method/helper