Further cleanup. Moved BackgroundJob Task enqueues into TaskScheduler, so I can have complete control via one interface.

API/Interfaces/ITaskScheduler.cs

@@ -2,6 +2,8 @@
 {
     public interface ITaskScheduler
     {
-        
+        public void ScanLibrary(int libraryId, bool forceUpdate = false);
+
+        public void CleanupVolumes(int[] volumeIds);
     }
 }