Update git submodules

Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge "Generate pod.yaml from current context"
  - Generate pod.yaml from current context

    We want to generate pod.yaml from Heat contexts so we can
    re-use the context without destroying it.

    But we don't have node role information and it doesn't
    make sense in this case, so make the role optional.

    Since we changed Heat to use pkey instead of key_filename,
    we can embed the pkey into the pod.yaml, but we have
    to make sure to convert the pkey to string, in case
    it is a RSAKey object

    Change-Id: Ibefcfbd8236e68013a704c39964cb870da825da8
    Signed-off-by: Ross Brattain <ross.b.brattain@intel.com>