Include node_preparation inventory and playbook

[satheesaran]

Node preparation is required for hyperconverged environment, when one of the node goes faulty.
In this case, the new host that is brought in to the cluster, needs to be configured ahead. This configuration includes disabling gluster hooks, creating glusterfs slice, creating gluster bricks based same as on the faulty brick, opening the required ports using firewall, etc. All these tasks are automated with ansible playbook, and the template for such the inventory file is now included with gluster-ansible playbooks template directory. Also included the playbook under tasks

1. node_prep_inventory.yml - Template inventory file for node preparation,
                             before node replacement
2. node_prep.yml - Playbook use for node preparation