NFS server: export filesystems with crossmnt + no_subtree_check b…

…y default.

Although slightly insecure, these options make NFS mounts behave more
like local mounts, which is what most of us expect.  And then there's
always the possibility of overriding default options if you don't like it.

elasticluster/share/playbooks/roles/nfs-server/tasks/main.yml

@@ -44,7 +44,7 @@
   nfsexport:
     path='{{item.path}}'
     clients='{{item.clients}}'
-    options='{{item.options|default("rw,no_root_squash,async")}}'
+    options='{{item.options|default("rw,no_root_squash,async,no_subtree_check,crossmnt")}}'
     dest='/etc/exports'
     state=exported
   with_items: '{{NFS_EXPORTS}}'