switch to better type checking for lists, force plugin_instance to be string, fixup for service names containing x2d escape
switch to better type checking for lists, force plugin_instance to be string, fixup for service names containing x2d escape

maier/cadvisor-collectd,maier/cadvisor-collectd,AppliedInfrastructure/docker-metrics-collector,AppliedInfrastructure/docker-metrics-collector