CMM: allow different debug levels per logger/component

[msune]

Specially for development purposes, there should be a way to set at least the following loggers with different debug levels:

• Endpoints C++ logger (ROFL-common)
• xDPd's system and driver C logger
• Pipeline logger (ROFL-pipeline)

The behaviour should be as follows:

1. If the logging level is set via CLI with -d LEVEL this should overwrite any other plugin (as it does right now). The logging level should override any plugin
2. The system_manager should have an optional parameter to define the scope of the setting. Default should be ALL
3. At least the config plugin should allow the set of the different levels per logger.