MaxScale can time out systemd if startup of services takes too long

This relates to the fix to MXS-35 which makes MaxScale wait until it has daemonized itself and that all services have been started before exiting. This causes a problem if the startup takes longer than the default timeout of 90 seconds.

Either a timeout in the maxscale.service file needs to be added or a way to start MaxScale without waiting for the services to start needs to be added. The preferred option would be to increase the timeout in maxscale.service.