Update git submodules

Update git submodules

* Update docs/submodules/yardstick from branch 'stable/fraser'
  - Merge "Remove __init__ method overriding in HeatContextTestCase" into stable/fraser
  - Remove __init__ method overriding in HeatContextTestCase

    Unit test case clases should implement setUp() method instead of overriding
    __init__() method.

    JIRA: YARDSTICK-1210

    Change-Id: I0f9a10575f9aeebf76dfa84619e59589b3ea83f6
    Signed-off-by: Rodolfo Alonso Hernandez <rodolfo.alonso.hernandez@intel.com>
    (cherry picked from commit 619bed631f064a94ab20ac296802d467ebe32318)