Task #8888: Service is a frombus listener, so inherit from new class AbstractBusListener -> refactored out duplicate code

Task #8888: added abstract class AbstractBusListener to listen on a bus, and let the user implement one simple handle_message method

Task #8746 Adding a error_tolerance option to the executable_args master script. This controls if the step exits at the first error or if a pipeline should continue with the successfull processed steps. Usage in the parset on a step by step basis: stepname.control.error_tolerance=<Bool>

Task #8898: Write logfiles to CWD (allowing environment to go to $LOFARROOT, which cannot be used in stdxxx_logfile in supervisord < 3.2