Rails new app
Added books model scaffold.
Added users model scaffold.
Added roles minimal support to users model.
Added loans model scaffold.
Added some validations to models.
Added relations to users and books models.

Changed loans::_form partial to use collection
when selecting books and users.
Added devise gem.
Added TODO.

Removed comments in routes.db
Removed unwanted tracked content
Showing email of user in scaffolded view.
Added sign_in/sign_out/sign_up links.
Added cancan gem.

Added initial authorization support.
Updated TODO
Added better_errors gem for obvious reason.