Auto-Organize: Async operation and instant feedback UI (reworked)

This commit includes changes to enable and stabilize asyncronous
operation in the auto-organize area. Here are the key points:

- The auto-organize correction dialog is now closed (almost) instantly.
This means that the user does not have to wait until the file copy/move
operation is completed in order to continue. (even with local HDs the
copy/move process can take several minutes or even much longer with
network destination).
- This commit also implements locking of files to be organized in order
to prevent parallel processing of the same item. In effect, there can be
2 or more manual organization operations active even while the normal
auto-organization task is running without causing any problems
- The items that are currently being processed are indicated as such in
the log with an orange color and a spinner graphic
- The client display is refreshed through websocket messages
- A side effect of this is that other clients showing the auto-organize
log at the same time are always up-to-date as well

MediaBrowser.Server.Implementations/FileOrganization/EpisodeFileOrganizer.cs

@@ -272,6 +272,18 @@ namespace MediaBrowser.Server.Implementations.FileOrganization
 
             var originalExtractedSeriesString = result.ExtractedName;
 
+            bool isNew = string.IsNullOrWhiteSpace(result.Id);
+
+            if (isNew)
+            {
+                await _organizationService.SaveResult(result, cancellationToken);
+            }
+
+            if (!_organizationService.AddToInProgressList(result, isNew))
+            {
+                throw new Exception("File is currently processed otherwise. Please try again later.");
+            }
+            
             try
             {
             // Proceed to sort the file
@@ -363,6 +375,10 @@ namespace MediaBrowser.Server.Implementations.FileOrganization
                 _logger.Warn(ex.Message);
                 return;
             }
+            finally
+            {
+                _organizationService.RemoveFromInprogressList(result);
+            }
 
             if (rememberCorrection)
             {