Customize attributes (AWS)

These changes helped me get the trunk version working in AWS Opsworks.
Opsworks does not have Chef roles/search so I didn't manage to get the 1.4 branch going yet
It does however allow you to layer cookbooks and override recipes/attributes/templates.

I have made the same proposal to elasticsearch/cookbook-elasticsearch#208

ZMQ also doesn't install nicely on Amazon Linux due to it's major_version not matching a CentOS release, so I've put in a quick hack for that.