Update git submodules

Update git submodules

* Update docs/submodules/functest from branch 'stable/euphrates'
  - Merge "Remove securityscanning testcase" into stable/euphrates
  - Remove securityscanning testcase

    As the project is no longer released [1], security_scan is removed
    from testcases config files.

    It stops installing the related python package too.

    [1] https://lists.opnfv.org/pipermail/opnfv-tech-discuss/2017-September/017951.html

    Conflicts:
          upper-constraints.txt

    Change-Id: Ieb9ff4c2975fbf2c85b875a088b0ec18503a3722
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>
    (cherry picked from commit 59999eb2f2bf3b28c50a9b75fc551192450d28e3)