add "--log_level LEVEL" command line option and edit log levels of
syslog messages

	modified:   src/bruce/anomaly_tracker.cc
	modified:   src/bruce/batch/combined_topics_batcher.cc
	modified:   src/bruce/bruce.cc
	modified:   src/bruce/bruce.test.cc
	modified:   src/bruce/bruce_server.cc
	modified:   src/bruce/config.cc
	modified:   src/bruce/config.h
	modified:   src/bruce/input_thread.cc
	modified:   src/bruce/mock_kafka_server/cmd_handler.cc
	modified:   src/bruce/msg_dispatch/dispatcher_shared_state.cc
	modified:   src/bruce/msg_dispatch/kafka_dispatcher.cc
	modified:   src/bruce/msg_dispatch/receiver.cc
	modified:   src/bruce/msg_dispatch/sender.cc
	modified:   src/bruce/router_thread.cc
	modified:   src/bruce/util/misc_util.cc
	modified:   src/bruce/util/msg_util.cc
	modified:   src/bruce/util/time_util.cc