Periodically check cluster job and update job info to database

[Fizzbb]

Given an interval (e.g. 30 seconds), 1)list all the jobs, mpijobs, unified job; 2) find job associated pods, extract job status(pending/running/done/fail..) and associated pods resource utilizations (gpu, cpu, memory, network ...), 3) save to the info to MongoDB

Notes
1)avoid duplicated info due to custom job built on kubernetes job, e.g., mpijob will create job and then pods.

[Fizzbb]

1. GPU metrics are not merged to the Pod metrics. To get GPU utilization and GPU memory utilization, need to map from pod name to gpu process id. Refer to previous functions in app.py. A pod could use multiple GPUs and even cross nodes.
2. Debug mongo records with duplicate keys.