Update git submodules

* Update docs/submodules/functest from branch 'master'
  - Define download_images.sh and check_os.sh as scripts

    It also updates all python scripts which call check_os.sh.
    The former healthcheck.sh is removed.

    No shell script must be executable in git.

    Change-Id: If4e8deb50ebd635a9091e3bb79ef61c07b9660dc
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/functest b/docs/submodules/functest
index 6786096..1b838b4 160000 (submodule)
--- a/docs/submodules/functest
+++ b/docs/submodules/functest
@@ -1 +1 @@
-Subproject commit 678609610f4ccbcb19438cbce5d84bd376010596
+Subproject commit 1b838b4bd75f21e45e8a40407b1e3279dd5935d2