Define Puppet cert attribute OIDs

This commit defines an initial set of OIDs for private use within Puppet. The
defined OIDs are focused toward identifying node information that is
embedded in a node certificate.
Merge pull request #2085 from adrienthebo/feature/puppet-custom-oids

Define Puppet cert attribute OIDs
Merge branch 'master' of https://github.com/puppetlabs/puppet