Allow starting the worker with no conf.json file present

[naorlivne]

Expected/Wanted Behavior

The worker should work even without any config file existing if it has all the needed params given as envvars.

Actual Behavior

Currently this is worked around by having an empty config file in the root of the repo but a conf.json file is still needed to exist or the start will fail.

How to fix

We need to check if the conf.json exists before reading from it and if it doesn't exist set the auth_file var to be an empty dict.

[naorlivne]

Fixed in latest, will be added to the next numbered release.