Unify and standardize inventory_hostname

This was causing some confusing conflicts, so create a new fact called
"this_node" which is inventory_hostname.split('.')[0], i.e. the short
name, and use that everywhere instead of an FQDN or true inventory
hostname.

roles/pvc/templates/zookeeper/zoo.cfg.j2

@@ -21,7 +21,7 @@ autopurge.purgeInterval=1
 
 # Listen on port 2181 on the cluster IP
 clientPort=2181
-clientPortAddress={% for node in pvc_nodes if node.hostname == inventory_hostname %}{{ node.cluster_ip }}{% endfor %}
+clientPortAddress={% for node in pvc_nodes if node.hostname == this_node %}{{ node.cluster_ip }}{% endfor %}
 
 # Node list - all coordinators
 {% for node in pvc_nodes if node.is_coordinator %}