Patch contains next changes:

* Platform code changed. Now it has no "config_file" arg. Instead of this
  arg, you can specify cert args or token args. Or use sys-env rally env create
  flag.

* "sleep_time" and "retries_total" moved as rally config opts. Use it instead of
  these args. See rally_plugins/common/opts.py to learn new opts.

* Pod's scenario changed. Now it called "Kubernetes.create_and_delete_pod"
  and don't contains sleep_time and retries_total args.

* "kubernetes.namespace" context deprecated. Use "namespace" context instead.

Change-Id: I93f19ac447cf6982a73008e832b71b141e812fe6