Add hiera example

Now that we have a basebox with Puppet 3.x, thanks @garethr

Uses Vagrant's own shared folder to pass `hiera.yaml` and `hieradata` in.
Fairly simple search hierachy and an empty `common.yaml` to get started.

The order of `hostname` and `environment` has been switched so that
individual nodes can override specific keys from the environment's config.
This differs from Perf Platform, cc @samjsharpe

Currently passing a `--hiera_config` option to Puppet, but this can be
replaced with `puppet.hiera_config_path` in Vagrant 1.2.3