Update git submodules

* Update docs/submodules/functest from branch 'master'
  - Move rally and tempest to requirements.txt

    As rally and tempest are called when preparing env, they are
    considered as dependencies. It also modifies on-the-fly
    upper-contraints.txt to allow cloning the git repository.

    Change-Id: I72e809d4cf15f9f2539a74fce1c6eb444d8c3b47
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/functest b/docs/submodules/functest
index 9916cd3..1bcc91c 160000 (submodule)
--- a/docs/submodules/functest
+++ b/docs/submodules/functest
@@ -1 +1 @@
-Subproject commit 9916cd3fbd116762a84ca3a81dd08315d0b747cd
+Subproject commit 1bcc91c7ba00738dbc7d25422bc957d4cbf3f3ba