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/HostConfigModule.cs

@@ -0,0 +1,55 @@
+using System.Linq;
+using System.Reflection;
+using FluentValidation;
+using NzbDrone.Core.Configuration;
+using Omu.ValueInjecter;
+
+namespace NzbDrone.Api.Config
+{
+    public class HostConfigModule : NzbDroneRestModule<HostConfigResource>
+    {
+        private readonly IConfigFileProvider _configFileProvider;
+
+        public HostConfigModule(ConfigFileProvider configFileProvider)
+            : base("/config/host")
+        {
+            _configFileProvider = configFileProvider;
+
+            GetResourceSingle = GetHostConfig;
+            GetResourceById = GetHostConfig;
+            UpdateResource = SaveHostConfig;
+
+            SharedValidator.RuleFor(c => c.Branch).NotEmpty().WithMessage("Branch name is required, 'master' is the default");
+            SharedValidator.RuleFor(c => c.Port).InclusiveBetween(1, 65535);
+            
+            SharedValidator.RuleFor(c => c.Username).NotEmpty().When(c => c.AuthenticationEnabled);
+            SharedValidator.RuleFor(c => c.Password).NotEmpty().When(c => c.AuthenticationEnabled);
+
+            SharedValidator.RuleFor(c => c.SslPort).InclusiveBetween(1, 65535).When(c => c.EnableSsl);
+            SharedValidator.RuleFor(c => c.SslCertHash).NotEmpty().When(c => c.EnableSsl);
+        }
+
+        private HostConfigResource GetHostConfig()
+        {
+            var resource = new HostConfigResource();
+            resource.InjectFrom(_configFileProvider);
+            resource.Id = 1;
+
+            return resource;
+        }
+
+        private HostConfigResource GetHostConfig(int id)
+        {
+            return GetHostConfig();
+        }
+
+        private void SaveHostConfig(HostConfigResource resource)
+        {
+            var dictionary = resource.GetType()
+                                     .GetProperties(BindingFlags.Instance | BindingFlags.Public)
+                                     .ToDictionary(prop => prop.Name, prop => prop.GetValue(resource, null));
+
+            _configFileProvider.SaveConfigDictionary(dictionary);
+        }
+    }
+}