Downgrade metadata-json-lint for Ruby 1.9
Downgrade metadata-json-lint for Ruby 1.9

Without this change, tests fail. `metadata-json-lint` is not supported on
Ruby 1.9, but versions of the gem prior to 1.2.0 happen to work for our
purposes. This downgrades `metadata-json-lint` when using Ruby 1.9.

daveseff/puppetlabs-aws,puppetlabs/puppetlabs-aws,daveseff/puppetlabs-aws,gregohardy/puppetlabs-aws,gregohardy/puppetlabs-aws,puppetlabs/puppetlabs-aws