Add debug output to the CLI

[AlCalzone]

In order to debug issues with the CLI, it would be nice to enable some log output. The debug module is pretty good for that, as it allows us to run the CLI commands with the DEBUG variable set, e.g.: $ DEBUG=* iobroker host this

[Apollon77]

Would a general "--debug" parameter also be an idea?

[AlCalzone]

The previous idea is ready-to-implement, we would just need to add the the module and sprinkle debug("...") calls where appropriate. --debug would require custom logic and I don't think it is required that often.