Flush stdout to avoid getting buffered results.

I am currently using python-iptable in a worker launched by supervisor. The worker is writing on stdout and when i am reading rules, i am get an invalid result (incomplete rules). Launching the worker without supervisor is working fine.

This worked fine for me before c0f40e6952f98001633bf2536b398bb78db9d8b9.

I investigated and found out that the stdout was no longer flushed, and i was getting the previously printed result.