Update git submodules

Update git submodules

* Update docs/submodules/functest from branch 'master'
  - Merge "Conform the RefStack testcase with the Rally context"
  - Conform the RefStack testcase with the Rally context

    If the RefStack testcase relies on the Tempest configuration
    generated by Rally, it must conforms with the related context [1].

    [1] https://raw.githubusercontent.com/openstack/rally/0.9.1/rally/plugins/openstack/verification/tempest/context.py

    Change-Id: Ia62c0a328c53a1541aeaf8668e1f34ae67898eed
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>