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/NzbDrone.Api/Config/IndexerConfigModule.cs

@@ -0,0 +1,15 @@
+using FluentValidation;
+using NzbDrone.Core.Configuration;
+
+namespace NzbDrone.Api.Config
+{
+    public class IndexerConfigModule : NzbDroneConfigModule<IndexerConfigResource>
+    {
+
+        public IndexerConfigModule(IConfigService configService)
+            : base(configService)
+        {
+            SharedValidator.RuleFor(c => c.RssSyncInterval).InclusiveBetween(10, 120);
+        }
+    }
+}