Update git submodules

* Update docs/submodules/yardstick from branch 'stable/fraser'
  - Merge "Replace nova delete instance with shade client." into stable/fraser
  - Replace nova delete instance with shade client.

    Function delete_instance now uses shade client.

    JIRA: YARDSTICK-1088

    Change-Id: I5772a74c6dc2d103edd410042a8eaf721d1bcc5c
    Signed-off-by: Shobhi Jain <shobhi.jain@intel.com>
    (cherry picked from commit 05f97c4e4ce1e8c7c97cda16f12215e663a13c23)

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 8c76399..8ebc5f4 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 8c76399ed61bb1256dddab909a23838cb6fa498e
+Subproject commit 8ebc5f4ac22fdaf493f2120997afdb5f3a6c10c1