Change default logging: level "WARNING" and up to the console

[lucmurer]

At the moment we do not log anything if not explicitly requested. For some functionality this is sub-optimal, for example when just some tokens from the Hashicorp-Vault cannot be replaced. Should we exit then? Probably no. But with the current default logging configuration the user will not see any message about what went wrong with the devices where no data could be got.

So we should do the following:

• Change the default log settings (if nothing else is configured or requested by command line) to "log to console" and level "WARNING".
• Make sure, that the urllib & Co. logs do not spam our logs
• Change the "enable logging" command line switch ("-l") to a "quiet" switch ("-q") to suppress logging.