Update git submodules

* Update docs/submodules/functest from branch 'master'
  - Merge "Give a list of links to wget"
  - Give a list of links to wget

    Now download_images.sh simply relies on wget -i.
    It downloads all requirements as the biggest ones are mandatory or
    scenario independent (VNF)

    The offical ubuntu-16.04-server-cloudimg-amd64-disk1.img is
    selected instead of the one hosting by OPNFV SDNVPN.

    Change-Id: Ica566bb351f22dfba001678fe93b8a2b1523941a
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/functest b/docs/submodules/functest
index 42562fa..c721018 160000 (submodule)
--- a/docs/submodules/functest
+++ b/docs/submodules/functest
@@ -1 +1 @@
-Subproject commit 42562fa3393aa54d1780a428b439cedcd3590a7b
+Subproject commit c72101846e7fa0b6c4a32683b14e87adde8b59ec