Added contact email to user agent

MusicBrainz request a contact email address is supplied in comment section of user agent field.

Emby.Server.Implementations/ApplicationHost.cs

@@ -428,6 +428,12 @@ namespace Emby.Server.Implementations
         /// <value>The application user agent.</value>
         public string ApplicationUserAgent => Name.Replace(' ','-') + "/" + ApplicationVersion;
 
+        /// <summary>
+        /// Gets the email address for use within a comment section of a user agent field.
+        /// Presently used to provide contact information to MusicBrainz service.
+        /// </summary>
+        public string ApplicationUserAgentAddress { get; } = "team@jellyfin.org";
+
         private string _productName;
 
         /// <summary>