Add api to get child nodes information

Added an api to get child-node information, this is very useful to understand the nodes and if they are available for schedule and what is running on where, and the main objective is to allow monitoring and automation when managing cluster.

Use case: Kubernetes, I had a bunch of trouble trying to figure out why child nodes were not working correctly, this helps with that and allow for a simple cron job to monitor in case a child node is overloaded but others are not, metrics, etc.

Still missing cgroup awareness to be better supported on Kubernetes, I'm working on that next.