Fix nfs role issues based on molecule testing

Based on Molecule testing fix following issues on
nfs role.

 - enable nfs services (previously only started)
 - create handler for exportfs to deal idempotency
 - add all kubernetes nodes to exports as it was dependent on ansible inventory order wheather correct hosts was on the list
 - add inventory_hostname as default host incase ansible_host variable not defined.

Issue-ID: OOM-1756

Change-Id: Ib93e9d2a9cf49003d04dd5f890294eda1eb966ff
Signed-off-by: Samuli Silvius <s.silvius@partner.samsung.com>
diff --git a/ansible/roles/nfs/templates/exports.j2 b/ansible/roles/nfs/templates/exports.j2
index 1f6956c..c605d9b 100644
--- a/ansible/roles/nfs/templates/exports.j2
+++ b/ansible/roles/nfs/templates/exports.j2
@@ -1,3 +1,3 @@
-{% for host in groups.kubernetes[1:] -%}
-    {{ nfs_mount_path }}  {{ hostvars[host].ansible_host }}(rw,sync,no_root_squash,no_subtree_check)
+{% for host in groups.kubernetes -%}
+    {{ nfs_mount_path }}  {{ hostvars[host].ansible_host | default(hostvars[host].inventory_hostname) }}(rw,sync,no_root_squash,no_subtree_check)
 {% endfor %}