Update git submodules

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>