Added deletion of snapshot's metadata files during clean of old snapshots

Change-Id: Id51bcbd6eb0080e2f93259e774f4d9c8df999f50
diff --git a/trsync.py b/trsync.py
index beed363..3dcbdd6 100644
--- a/trsync.py
+++ b/trsync.py
@@ -189,6 +189,8 @@
                            ]
                 if not s_links:
                     self.rmdir(s_path)
+                    self.rmfile(s_path + '.target.txt')
+                    self.rmfile(s_path + '.diff.txt')
                 else:
                     self.logger.info('Skip deletion of "{}" because there are '
                                      'symlinks found: {}'.format(s, s_links))