DBIx::Class::ResultSource right into your attribute definitions and will
automatically call it when it finds an add_column attribute option. It also
replaces the DBIx::Class-generated accessor methods (these are
Class::Accessor::Grouped-generated accessor methods under the hood) with the
Moose-generated accessor methods so that you can use more of the wonderful
powers of Moose (eg. type constraints, triggers, ...).
