Restart automatically workers after a set number of requests

Workaround for memory leaks (current and future ones) #458 (closed)

Workers restart seamlessly with this message:

[2020-10-02 08:14:22 +0000] [894752] [INFO] Autorestarting worker after current request.
[2020-10-02 08:14:22 +0000] [894752] [INFO] Worker exiting (pid: 894752)
[2020-10-02 08:14:22 +0000] [894891] [INFO] Booting worker with pid: 894891