Merge pull request #2782 from JustAMan/fix-ssa-delivery

Fix support for attachments with baseURL set

(cherry picked from commit 6386b9b1b99ac73056d871c3927df68989c92003)
Signed-off-by: Joshua M. Boniface <joshua@boniface.me>

MediaBrowser.Api/Playback/MediaInfoService.cs

@@ -573,8 +573,7 @@ namespace MediaBrowser.Api.Playback
             {
                 attachment.DeliveryUrl = string.Format(
                     CultureInfo.InvariantCulture,
-                    "{0}/Videos/{1}/{2}/Attachments/{3}",
-                    ServerConfigurationManager.Configuration.BaseUrl,
+                    "/Videos/{0}/{1}/Attachments/{2}",
                     item.Id,
                     mediaSource.Id,
                     attachment.Index);