Warning indicator for services

[bobf]

Implement a traffic light warning indicator in each service row.

Green: all tasks present and in "running" state; all tasks using < 50% CPU limit; all tasks using < 50% RAM limit
Yellow: any task missing or not in "running" state; any task using >= 50% CPU limit; any task using >= RAM limit
Red: > 1 task missing or not in "running" state; any task using > 90% CPU limit; any task using > 90% RAM limt