Add some more sample lists
Add a FIXME about displaying lists from relevant libraries
Make it possible to edit (information about) lists in admin
Make it possible to delete lists
Make sure the unchecked genre checkbox is saved as 0 not NULL
Make it possible to add lists
Make it possible to delete books from lists

This also changes how _get_library_for_admin_user is called. I'll
fix other places it is used in the next commit.
Fix call to _get_library_for_admin_user() in /admin route
Make it possible to add books to lists
Make it easier to remove several books from a list