HA keepalived work

This partially resolves https://trello.com/c/LVS8Ly87

* Add notify_stop to the provider
* Provide a script to setup iptables and ip rules for the VIPs
* Add a boolean node["keepalived"]["global"]["notification_emails"] for
  notification emails.  This prevents SMTP notifications when no SMTP
  server or email address have been defined.  Set this boolean to true
  if you want to send email notifications.