Get rid of trailing comma in lists of lists and genres on book pages
Make sure only lists and genres for the current library is displayed in breadcrumbs on book page
Create a separate template for the login form
Move login routes to a package, change /log/in to /login and /log/out to /logout
Remove /about in favour of /page/:slug
Move routes for comments to a separate file. Do not use in main file.
Fix a couple of missing dependencies in Ebooksforlib::Route::Login
Fix a couple of missing dependencies in Ebooksforlib::Route::Comments
Move routes for ratings to a separate file. Do not use in main file.
Use /in and /out for login/logout

I can't seem to be able to override the builtin /logout of
Dancer::Plugin::Auth::Extensible...
Enable admin login

If a non-logged in user visits /admin, she is redirected to
/in?admin=1, which makes sure realm=local is included in the
login form, and the user is authenticated against the "local"
realm, which is the realm for admins and superadmins.

Not sure if this is the prefect solution, but it works for now.

Possible problems:
- An admin user who fails to log in is redirected to /in
Fix failed login redirect for admin users
Fix login for superadmin users
Add 'days' to the loan period on /my
Remove reduntant many_to_many relationships
Make it possible to return loans

PLEASE NOTE: Due to a bug, old loans are not recorded in the
old_loans table. To be continued...