Validation, settings UI cleanup and different settings models, oh my

New: Download client UI matches other settings
Fixed: Prevent drone factory folder from being set to invalid paths/root path for series
Fixed: Switching pages in settings will not hide changes
Fixed: Test download clients
Fixed: Settings are validated before saving

src/UI/Settings/Indexers/IndexerSettingsModel.js

@@ -0,0 +1,11 @@
+'use strict';
+define(
+    [
+        'Settings/SettingsModelBase'
+    ], function (SettingsModelBase) {
+        return SettingsModelBase.extend({
+            url           : window.NzbDrone.ApiRoot + '/config/indexer',
+            successMessage: 'Indexer settings saved',
+            errorMessage  : 'Failed to save indexer settings'
+        });
+    });

src/UI/Settings/Indexers/Options/IndexerOptionsView.js

@@ -2,12 +2,16 @@
 define(
     [
         'marionette',
-        'Mixins/AsModelBoundView'
-    ], function (Marionette, AsModelBoundView) {
+        'Mixins/AsModelBoundView',
+        'Mixins/AsValidatedView'
+    ], function (Marionette, AsModelBoundView, AsValidatedView) {
 
         var view = Marionette.ItemView.extend({
             template: 'Settings/Indexers/Options/IndexerOptionsViewTemplate'
         });
 
-        return AsModelBoundView.call(view);
+        AsModelBoundView.call(view);
+        AsValidatedView.call(view);
+
+        return view;
     });