Unnecessary warnings/exceptions when shutting down VMWorkers

[abyrne55]

When a VMWorker transitions into the OFF state, sometimes the pkill command fails to halt the corresponding VM before it makes another worker request. This triggers the following warning/exception:

Aug 19 13:36:57 beaglebone python3[20799]: WARNING:root:VMWorker104 made request but no output events set

and/or

Aug 19 13:36:57 beaglebone python3[20799]: ----------------------------------------
Aug 19 13:36:57 beaglebone python3[20799]: Exception happened during processing of request from ('192.168.1.104', 42042)
Aug 19 13:36:57 beaglebone python3[20799]: Traceback (most recent call last):
Aug 19 13:36:57 beaglebone python3[20799]:   File "/usr/lib/python3.7/socketserver.py", line 650, in process_request_thread
Aug 19 13:36:57 beaglebone python3[20799]:     self.finish_request(request, client_address)
Aug 19 13:36:57 beaglebone python3[20799]:   File "/usr/lib/python3.7/socketserver.py", line 360, in finish_request
Aug 19 13:36:57 beaglebone python3[20799]:     self.RequestHandlerClass(request, client_address, self)
Aug 19 13:36:57 beaglebone python3[20799]:   File "/usr/lib/python3.7/socketserver.py", line 720, in __init__
Aug 19 13:36:57 beaglebone python3[20799]:     self.handle()
Aug 19 13:36:57 beaglebone python3[20799]:   File "/home/debian/MicroFaaS/orchestrator.py", line 103, in handle
Aug 19 13:36:57 beaglebone python3[20799]:     self.data = self.request.recv(12288).strip()
Aug 19 13:36:57 beaglebone python3[20799]: ConnectionResetError: [Errno 104] Connection reset by peer
Aug 19 13:36:57 beaglebone python3[20799]: ----------------------------------------

These warnings/exceptions can be safely caught and ignored, as pkill ensures the VM is properly shut down, even if it lets a few erroneous worker requests slip out during the second or two it needs to kill QEMU.

(Note that this is in reference to code that's currently on the refactor branch.)

[abyrne55]

Hopefully fixed by 57edd69