- fix shell script issues
  - `bx` is deprecated; rename to `ibmcloud`
  - remove unnecessay variable replacement in hollow-node_template.yaml
  - add replacement logic for HOLLOW_KUBELET_TEST_ARGS and HOLLOW_PROXY_TEST_ARGS
  - don't hardcode KUBEMARK_IMAGE_REGISTRY to brandondr96
- make cluster number and spec configurable
  - make number and spec of workers configurable
  - separate NUM_NODES and KUBEMARK_NUM_NODES