add StopJob method to IFileJob

Author: andreaskueffel

FileSyncLibNet/Commons/IFileJob.cs

@@ -8,6 +8,7 @@ namespace FileSyncLibNet.Commons
 {
     public interface IFileJob
     {
+        void StopJob();
         void StartJob();
         void ExecuteNow();
         Task ExecuteNowASync();