Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge "Make uwsgi app to not demonize"
  - Make uwsgi app to not demonize

    Supervisord doesn't support demonize applications, thus we have to
    make the uwsgi application to run not in background.

    - Fixed Yardstick API path.
    - Fixed HttpClient class to raise correct exception when
      the HTML response (not JSON) like 4xx, 5xx is received.
      (http://docs.python-requests.org/en/master/user/quickstart/#json-response-content)

    JIRA: YARDSTICK-1297

    Change-Id: I4d1c1bb7266eeed0bd357bd28b91206d1580611f
    Signed-off-by: Mytnyk, Volodymyr <volodymyrx.mytnyk@intel.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 70e0f37..8d4aead 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 70e0f379bffcd0837fea69bdac5e9148270e257b
+Subproject commit 8d4aeadbd2a9dd7f0b8371dc53de5f4b372800b0