move create_lesson method to ApplicationController so it's global
add student name to lesson show page
pass lesson booking info to sign up/in and create lesson after signed in

https://app.asana.com/0/10062427228782/10063719499859
move RegistrationsController to users folder
enable login with Facebook
move additional user info (outside of email/password) to user edit page
add link to profile in nav bar
move after_create logic for creating lesson to session instead of params

https://app.asana.com/0/10062427228782/10148977561291