- Fetches nodes status [CPU and Memory: allocatable and capacity]
- Fetches nodes metrics [CPU and Memory: usage]
  - For this we had to add a new k8s api
  - Metrics are only fetched if cluster is provide by GCP,
    since other provider might not implement the metrics server
- Exposes node data to the FE via ClusterSerializer#represent_list
- Adds and refactor specs