Update git submodules

Update git submodules

* Update docs/submodules/functest from branch 'master'
  - Merge "Update rally image name regex"
  - Update rally image name regex

    The default value doesn't conform with our image names.
    Else it downloads the image from internet which may be not possible
    (offline testing, proxy or deployment l3 issues [1])

    [1] https://build.opnfv.org/ci/view/functest/job/functest-apex-virtual-suite-master/113/console

    Change-Id: I7d951967784d591e7155fe8582299aaa9b680b10
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>