various fixes for the keepalived.conf pillars
    
    - sort alphabetically
    - add missing key in pillar/secrets/role/proxy.sls
    - the keys that shouldn't have arguments are supposed to have empty
      value on the pillars, not True (this used to work in the past, but not
      any more)
    - move the smtp_alert in vrrp_instances (should be there according to
      the docs)
    - typo in notification_email