Update git submodules

* Update docs/submodules/functest from branch 'master'
  - Stop redirecting output to json files

    Rally may print additional data to console which results in an
    invalid json files. The json files are generated via rally instead of
    dumping stdout.

    It's mandatory to backport the next bugfix [1] in stable/fraser.

    [1] https://gerrit.opnfv.org/gerrit/#/c/60265/

    Change-Id: Ifbd90e685a7b52c70b3110a46e3c7991eddc05f4
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/functest b/docs/submodules/functest
index 3630604..18c96ab 160000 (submodule)
--- a/docs/submodules/functest
+++ b/docs/submodules/functest
@@ -1 +1 @@
-Subproject commit 363060485f107bb0af09977e101abc54f1fa207c
+Subproject commit 18c96abe8b6a3d6e919ff7ba64952454830357b3