[Catalyst] Catalyst tutorial

[Octavian Râşniţă]

In Catalyst::Manual::Tutorial::04_BasicCRUD.pod I read that we need to 
specify the ResultSet classes we want to use with:

__PACKAGE__->resultset_class('MyApp::Schema::ResultSet::Book');

I've seen that it works even without it. Is this line really needed?

Octavian