Let Bind track data changes

Integrate new bind-dyndb-ldap features to automatically track
DNS data changes:

 1) Zone refresh
    Set --zone-refresh in installation to define number of seconds
    between bind-dyndb-ldap polls for new DNS zones. User now
    doesn't have to restart name server when a new zone is added.

 2) New zone notifications
    Use LDAP persistent search mechanism to immediately get
    notification when any new DNS zone is added. Use --zone-notif
    install option to enable. This option is mutually exclusive
    with Zone refresh.

To enable this functionality in existing IPA installations,
update a list of arguments for bind-dyndb-ldap in /etc/named.conf.
An example when zone refresh is disabled and DNS data change
notifications (argument psearch of bind-dyndb-ldap) are enabled:

dynamic-db "ipa" {
...
        arg "zone_refresh 0";
        arg "psearch yes";
};

This patch requires bind-dyndb-ldap-1.0.0-0.1.b1 or later.

https://fedorahosted.org/freeipa/ticket/826

install/share/bind.named.conf.template

@@ -44,4 +44,6 @@ dynamic-db "ipa" {
 	arg "auth_method sasl";
 	arg "sasl_mech GSSAPI";
 	arg "sasl_user DNS/$FQDN";
+	arg "zone_refresh $ZONE_REFRESH";
+	arg "psearch $PERSISTENT_SEARCH";
 };