Change type for private blog settings

refs #5614 and #5503

- update private blog type, including update to settings.edit
- switch order of populate settings & update fixtures + populate all settings

Private blog settings should not be returned by public endpoints
therefore they need a type which is not `blog` or `theme`.
`core` doesn't suit either, as those settings don't usually have UI
To resolve this, I created a new type `private` which can be used
for any setting which has a UI but should not be public data

ghost/admin/app/routes/settings/general.js

@@ -15,7 +15,7 @@ export default AuthenticatedRoute.extend(styleBody, CurrentUserSettings, {
     },
 
     model: function () {
-        return this.store.find('setting', {type: 'blog,theme'}).then(function (records) {
+        return this.store.find('setting', {type: 'blog,theme,private'}).then(function (records) {
             return records.get('firstObject');
         });
     },