Update git submodules

Update git submodules

* Update docs/submodules/functest from branch 'master'
  - Merge "Leverage on pbr (Python Build Reasonableness)"
  - Leverage on pbr (Python Build Reasonableness)

    pbr can inject requirements into the install_requires, tests_require
    and/or dependency_links arguments to setup. They were previously
    falsy unset.

    It also supports conditional dependencies which can be added to the
    requirements (e.g. subprocess32; python_version=='2.7').
    Then requirements.py3.txt is removed.

    It also removes functest/cli/setup.py which seems false and obsolete.

    Dockerfile is updated as well. One temporarily link is created because
    of several hardcoded paths in Functest.

    Change-Id: I14b3b25e07fbac490dd1d5ce943ec02c5b11f242
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>