Added sign up feature
Created User model
Fixed issues with Book and BookShelf models
Implemented user sign up
Wrote first failing sign in spec
Created the /signin route
Installed sorcery
Created sessions controller and new sessions view
Further set up the sessions routes and view
Implemented sign in to the point of setting up sorcery
Set up user model to use sorcery
Added the flash to the layout
Complete the valid sign in test
Added invalid sign in test
Added handling for failed login