croak import

This module does not know about croak, so if it tries to croak something like this will happen:

```Undefined subroutine &Dist::Zilla::Plugin::InsertCopyright::croak called at /usr/local/share/perl/5.14.2/Dist/Zilla/Plugin/InsertCopyright.pm line 51.```

Please note that I failed to do a dzil test, dist.ini seems outdated - our of scope for this pull request.