Damnit IE, you suck

Fixed: IE trying to save/open json result in settings
Empty allowed release group can be saved

NzbDrone.Web/Models/JsonNotificationResult.cs

@@ -45,8 +45,8 @@ namespace NzbDrone.Web.Models
             return new JsonResult
             {
                 Data = new JsonNotificationResult { NotificationType = notificationType, Title = title, Text = text },
-                ContentType = null,
+                ContentType = "application/json; charset=UTF-8",
-                ContentEncoding = null,
+                ContentEncoding = System.Text.Encoding.UTF8,
                 JsonRequestBehavior = JsonRequestBehavior.AllowGet
             };
         }

NzbDrone.Web/Models/MiscSettingsModel.cs

@@ -18,6 +18,7 @@ namespace NzbDrone.Web.Models
 
         [DisplayName("Specified Release Groups")]
         [Description("Comma separated list of release groups to download episodes (leave empty for all groups)")]
+        [DisplayFormat(ConvertEmptyStringToNull = false)]
         public string AllowedReleaseGroups { get; set; }
     }
 }