Fix bug where sync thread wouldn't start when backgrounded

The clue was here:
0eafeb557e/fuse.py (L861)

sn_fuse.py

@@ -34,6 +34,8 @@ class StandardNotesFUSE(LoggingMixIn, Operations):
         self.run_sync = Event()
         self.stop_sync = Event()
         self.sync_thread = Thread(target=self._syncThread)
+
+    def init(self, path):
         self.sync_thread.start()
 
     def destroy(self, path):