Add zonefile button to domain

app/views/admin/domains/show.haml

@@ -5,6 +5,7 @@
   .col-sm-6
     %h2.text-right.text-center-xs
       = link_to(t('shared.edit_statuses'), edit_admin_domain_path(@domain), class: 'btn btn-primary')
+      = link_to(t('generate_zonefile'), zonefile_admin_domain_path(@domain), class: 'btn btn-primary')
 
 %hr
 .row

app/views/admin/domains/zonefile.haml

@@ -1,2 +1,12 @@
-= preserve do
-  %pre= @zonefile
+.row
+  .col-sm-6
+    %h2.text-center-xs
+      = "#{t('zonefile')}"
+  .col-sm-6
+    %h2.text-right.text-center-xs
+      = link_to(t('shared.back_to_domain'), admin_domain_path(@domain), class: 'btn btn-default')
+%hr
+.row
+  .col-md-12
+    = preserve do
+      %pre= @zonefile

config/locales/en.yml

@@ -423,3 +423,5 @@ en:
   transfer_requested: 'Transfer requested.'
   message_was_not_found: 'Message was not found'
   host_obj_is_not_allowed: 'hostObj object is not allowed'
+  generate_zonefile: 'Generate zonefile'
+  zonefile: 'Zonefile'