Provide auto-injected environment parameters in cluster setup

Exporting instance IPs and host names as a environmental variable inside setup script. For example; if you are trying to setup ElasticSearch cluster, then ELASTICSEARCH_ADDRS and ELASTICSEARCH_HOSTS environmental variables will be exported.

See also JIRA issue USERGRID-146.
https://issues.apache.org/jira/browse/USERGRID-146

My iCLA is listed under "Salih Kardan"