older MooseX::SlurpyConstructor is bunk

e.g. see http://www.cpantesters.org/cpan/report/b4bab9ec-5f96-11e3-9dbf-9dfe62da64c8
Dist-Zilla-Plugin-MungeFile-WithData-0.006

          - bump prereq for MooseX::SlurpyConstructor to bypass old metaclass
            issues