fix race condition in config_server; endpoint_client sends logs to log server; endpoint_server: fix race and send logs to logsrv; ip discovery server now able to use central endpoint list for udp discovery sockets; fix log_record_client so it only reconnects if the old endpoint has been invalidated; merged log record server code into common/connectors; logs are pretty printed onto stdout when no connection to logsrv; fix zmq_utils issue to bind to ipv6 addresses