Support for "forward" statement

Add "forward" statement in options { } block in named.conf.

manifests/init.pp

@@ -2,6 +2,7 @@
 
 class bind (
     $forwarders            = '',
+    $forward               = undef,
     $dnssec                = true,
     $filter_ipv6           = false,
     $version               = '',

templates/named.conf.erb

@@ -20,6 +20,9 @@ options {
 		<%= forwarder %>;
 <%-   end -%>
 	};
+<%- end -%>
+<%- if @forward != '' -%>
+	forward <%= @forward %>;
 <%- end -%>
 	auth-nxdomain <%= @auth_nxdomain ? 'yes' : 'no' %>;
 	listen-on-v6 { any; };