Really fix localhost line in /etc/hosts
Really fix localhost line in /etc/hosts

This patch ensures that the localhost line in /etc/hosts is
configured properly prior to installing and configuring
RabbitMQ. Without this patch, the RabbitMQ installation often
fails on CentOS 7 since RabbitMQ can't figure out its hostname.

The fix in I6368b6584265084af6ff98caba68fc067b1f1f22 is reverted here
because it had no effect on the /etc/hosts file.

Change-Id: Ie65e5b7bcbaa1890824a93263c64e6fd04702852

openstack/openstack-ansible-rabbitmq_server,openstack/openstack-ansible-rabbitmq_server