Added metadata lint and puppet-syntax gems

metadata-json-lint is a little tool to check the validity of
Puppet metatdata.json files.

puppet-syntax tool check the validity of templates,manifests and hiera
files (the goal here is to replace manual checks in the gate by a
standard? check `rake syntax`).

Change-Id: I60b9cdfe27eeb8a8f5ad3a238dd847ed3096cb6b
Merge "Added metadata lint and puppet-syntax gems"