Check for valid URL in MetadataSource, Handle trailing slash

src/Lidarr.Api.V3/Config/MetadataProviderConfigModule.cs

@@ -2,6 +2,7 @@ using System.Linq;
 using System.Reflection;
 using NzbDrone.Core.Configuration;
 using Lidarr.Http;
+using NzbDrone.Core.Validation;
 
 namespace Lidarr.Api.V3.Config
 {
@@ -10,7 +11,7 @@ namespace Lidarr.Api.V3.Config
         public MetadataProviderConfigModule(IConfigService configService)
             : base(configService)
         {
-
+            SharedValidator.RuleFor(c => c.MetadataSource).IsValidUrl();
         }
 
         protected override MetadataProviderConfigResource ToResource(IConfigService model)

src/NzbDrone.Core/MetadataSource/SkyHook/SkyHookProxy.cs

@@ -287,7 +287,7 @@ namespace NzbDrone.Core.MetadataSource.SkyHook
         {
             if (_configService.MetadataSource.IsNotNullOrWhiteSpace())
             {
-                customerRequestBuilder = new HttpRequestBuilder(_configService.MetadataSource + "{route}/").CreateFactory();
+                customerRequestBuilder = new HttpRequestBuilder(_configService.MetadataSource.TrimEnd("/") + "/{route}/").CreateFactory();
             }
             else
             {