remove useless and confusing variable copying
MooseX::Role::Parameterized 1.03 removed MooseX::Role::Parameterized::Meta::Role::Parameterizable and replaced it with a trait

...which resulted in inscrutable JSON parsing errors, e.g.:
http://www.cpantesters.org/cpan/report/d9477ec4-2a59-11e4-851f-4f0c702f922a
http://www.cpantesters.org/cpan/report/16c5b698-2975-11e4-b4e0-df08702f922a
http://www.cpantesters.org/cpan/report/b30a515c-296c-11e4-bd34-9ad66f2f922a
http://www.cpantesters.org/cpan/report/a1773d8a-27e4-11e4-bbe2-5b65702f922a
http://www.cpantesters.org/cpan/report/6b1588ca-b9a6-11e3-aa24-b5c0dfbfc7aa
MooseX-Storage-0.47

  - report the versions of all JSON and YAML backends during tests, in an
    attempt to track down an elusive bug
  - now properly serializing attributes that are set to the undefined value
    (github #6, thanks, Jason Pope!)
  - fix compatibility problem with MooseX::Role::Parameterized 1.03+ and
    MooseX::Storage::Format::JSONpm (some internal details changed that we
    were relying on)