Update git submodules

Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge "Replace nova create instance with shade client."
  - Replace nova create instance with shade client.

    Remove redundant functions:
    *get_instances
    *get_instance_status
    *get_instance_by_name

    Function create_instance_and_wait_for_active now uses shade client.

    JIRA: YARDSTICK-1088

    Change-Id: I766da333dabbb1b83a7b4ede4bf73567ec70eb8c
    Signed-off-by: Shobhi Jain <shobhi.jain@intel.com>