Show an OpsWorks stack & hostname if this node was created by Opsworks (...

Hi:

We added these tweaks to your newrelic recipe so that it works with Amazon's AWS OpsWorks - if OpsWorks is in use (detected by node['opsworks']), then the hostname now includes the OpsWorks stack as a prefix. Without this, we were having problems with data getting conflated in NewRelic - we had servers named rails-app1, rails-app2, etc., in various OpsWorks stacks (e.g., production, demo, staging, etc.), but they all showed up in NewRelic as the same rails-apps1. Now, they show up in NewRelic as production-rails-app1, demo-rails-app2, etc.

Thanks!

-- Greg