More work on monitoring, add integration test

broker/src/hidra2_broker/server/server.go

broker/src/hidra2_broker/server/server_nottested.go

broker/src/hidra2_broker/server/server_test.go

broker/src/hidra2_broker/server/statistics.go

broker/src/hidra2_broker/server/statistics_writers.go

broker/src/hidra2_broker/utils/helpers.go

tests/broker/CMakeLists.txt

tests/broker/check_monitoring/CMakeLists.txt

tests/broker/check_monitoring/check_linux.sh

tests/broker/read_config/check_linux.sh

tests/broker/read_config/settings_bad.json

tests/settings/broker_settings.json