added guard for missing subdomain tutorial

public/javascripts/admin/tutorial.js

@@ -480,11 +480,18 @@ $(document).ready(function(){
       buttons: [{name: "Quit", onclick: guiders.hideAll},
                 {name: "Next"}],
       id: "settingseditwelcome",
-      next: "editsubdomain",
+      next: (function(){
+        if($('#site_subdomain').length > 0){
+          return "editsubdomain";
+        }else{
+          return "settingssave";
+        }
+      }()),
       overlay: true,
       title: "The Settings Page"
     });
 
+    if($('#site_subdomain').length > 0){
       guiders.createGuider({
         attachTo: "#site_subdomain",
         description: "Edit this field to change the subdomain of your site",
@@ -499,6 +506,7 @@ $(document).ready(function(){
           });
         }
       });
+    }
 
     guiders.createGuider({
       buttons: [],