Salt configuration for fluentd to Elasticsearch

This is a starting point for discussion with a view to changing this salt fluentd configuration to be optional and enabled with a flag during cluster creation time. @jbeda please can you have a look at this and please suggest the best way forward for me to change the config and other programs (kubeup.sh?) to make the fluentd to Elasticsearch optional? Thank you kindly.
It's implemented, but I've just left it out of this pull request. I will remove the comment and add it back when I do the PR for the Fluent GCP case.