helper for MooseX::Util to generate anonymous class names

 MooseX::TraitFor::Meta::Class::BetterAnonClassNames helps MooseX::Util's
 with_traits() method to create better named anonymous classes.
 .
  my $anon_class_name = with_traits('Zombie::Catcher', 'SomeTrait');
 .
 now becomes
 .
  Zombie::Catcher::__ANON__::SERIAL::1
 .
 rather than
 .
  Moose::Meta::Class::__ANON__::SERIAL::1