Update git submodules

Update git submodules

* Update docs/submodules/functest from branch 'stable/euphrates'
  - Add ${DOCKER_TAG} in Docker hooks

    It eases creating Docker images based on branches or tags.

    Conflicts:
    	docker/components/hooks/post_checkout
    	docker/features/hooks/post_checkout
    	docker/healthcheck/hooks/post_checkout
    	docker/restapi/hooks/post_checkout
    	docker/smoke/hooks/post_checkout
    	docker/vnf/hooks/post_checkout

    Change-Id: Id84513c53cad72a1fcd0debf06579481609b8bc2
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>
    (cherry picked from commit 29647efa114151d53ede5ba2d989593992c0b29f)