Add an All Results tab when filtering the site settings

app/assets/javascripts/admin/controllers/admin_site_settings_category_controller.js

@@ -16,6 +16,16 @@ Discourse.AdminSiteSettingsCategoryController = Ember.ObjectController.extend({
     }
   }.property('controllers.adminSiteSettings.content', 'categoryNameKey'),
 
+  emptyContentHandler: function() {
+    if (this.get('filteredContent').length < 1) {
+      if ( this.get('controllers.adminSiteSettings.filtered') ) {
+        this.transitionToRoute('adminSiteSettingsCategory', 'all_results');
+      } else {
+        this.transitionToRoute('adminSiteSettings');
+      }
+    }
+  }.observes('filteredContent'),
+
   actions: {
 
     /**

app/assets/javascripts/admin/controllers/admin_site_settings_controller.js

@@ -9,6 +9,7 @@
 Discourse.AdminSiteSettingsController = Ember.ArrayController.extend(Discourse.Presence, {
   filter: null,
   onlyOverridden: false,
+  filtered: Ember.computed.notEmpty('filter'),
 
   /**
     The list of settings based on the current filters
@@ -32,7 +33,7 @@ Discourse.AdminSiteSettingsController = Ember.ArrayController.extend(Discourse.P
 
     var self = this,
         matches,
-        matchesGroupedByCategory = Em.A();
+        matchesGroupedByCategory = Em.A([{nameKey: 'all_results', name: I18n.t('admin.site_settings.categories.all_results'), siteSettings: []}]);
 
     _.each(this.get('allSiteSettings'), function(settingsCategory) {
       matches = settingsCategory.siteSettings.filter(function(item) {
@@ -47,6 +48,7 @@ Discourse.AdminSiteSettingsController = Ember.ArrayController.extend(Discourse.P
         }
       });
       if (matches.length > 0) {
+        matchesGroupedByCategory[0].siteSettings.pushObjects(matches);
         matchesGroupedByCategory.pushObject({
           nameKey: settingsCategory.nameKey,
           name: settingsCategory.name,