Generate the list of nodes in cluster-vars.yml and etc-hosts from vagrant/ansible

[obnoxxx]

The vagrant file has the control over how many nodes are created and with which names and IP addresses. So we should not be maintaining the list of nodes in a second place (the cluster-vars.yml file that is used as an input for gluster-ansible). The node-list portion of this file should be generated.

[obnoxxx]

Now that we have had to add an /etc/hosts file to work around broken dns resolution of vm names from libvirt/dnsmasq, that file should be generated as well.