Rework config inheritance

[wneirynck]

The way the processes pass on their own configuration is fundamentally flawed. It has muliple issues:

• Serialization issues
• Processes don't always know which settings to pass on
• Settings can change between parent/child processes
• Security

This should be reworked to be more robust. Configuration should be set on "driver" level, instead of inferred from the process config.

[wneirynck]

A possible alternative approach is to have processes fetch their config from the api. The drawback here is that it becomes harder to reproduce any issues, since config can change between runs. Another solution is to have processes do everything via the api, and only pass on the api url and a token. This would make it much easier to pass on configuration (since there would be almost none), at the risk of introducing a new single point of failure. This would be mitigated by having multiple replicas of the api.