Forward X-Forwarded-Host header

(cherry picked from commit 3fbe4361386e9fb8dafdf82ad9f00f02bec746cc)

src/NzbDrone.Host/Startup.cs

@@ -58,7 +58,7 @@ namespace NzbDrone.Host
 
             services.Configure<ForwardedHeadersOptions>(options =>
             {
-                options.ForwardedHeaders = ForwardedHeaders.XForwardedFor | ForwardedHeaders.XForwardedProto;
+                options.ForwardedHeaders = ForwardedHeaders.XForwardedFor | ForwardedHeaders.XForwardedProto | ForwardedHeaders.XForwardedHost;
                 options.KnownNetworks.Clear();
                 options.KnownProxies.Clear();
             });