[BUG] The manager.py and agent.py is not stopping when it's requested

[rabits]

Issue description:

Right now the first term signal is just triggering the termination processes for the service, but not actually shutting down the service. Second one is terminating the process, but it's a second one. It should automatically shutdown when everything is stopped: Agent should stop when it's latest render is downloaded and Manager should stop when all the data is received from the Agents, processed and tasks were saved to continue later.

Environment:

• Application version: 0.2.0

Steps to reproduce:

Steps to reproduce the behavior:

1. Run BlendNet Agent or Manager
2. Press Ctrl-C
3. It will say about termination
4. Wait - it will do nothing
5. Press Ctrl-C again
6. The service is terminated

Additional

It's not critical for clouds (just a bit delaying the termination process), but for local provider it could be bad to maintenance.