add rpyc class and update Dockerfile

OpenshotService/openshot_video_generator.py

@@ -411,5 +411,6 @@ class video_service(rpyc.Service):
 
 from rpyc.utils.server import ThreadedServer
 t = ThreadedServer(video_service, port=8888)
-t.start()
 print('service started')
+t.start()
+