Load balancing containers

[elimaccoll]

To further optimize resource consumption down the road, start with a smaller pool of active containers for grading jobs and spin up more when high traffic is detected. Periods of high traffic will most likely come close to the due date of an assignment. Based on some currently undetermined metric, the number of grading containers would be scaled up to handle the increased traffic.

[blerner]

This is moot now, since k8s handles load balancing for us.