Update git submodules

* Update docs/submodules/dovetail from branch 'master'
  - Update OVP portal docker images for missing package

    - The missing futures packages was added in patch:
    https://gerrit.opnfv.org/gerrit/#/c/58833/
    - The patch above does resolve the issue and has
    been valdiated on a development instance.

    - The issue was likely introduced in patch
    https://gerrit.opnfv.org/gerrit/#/c/56623/

    Change-Id: I850947e386024e6b65514bdb518799c359234811
    Signed-off-by: Eddie Arrage <eddie.arrage@huawei.com>

diff --git a/docs/submodules/dovetail b/docs/submodules/dovetail
index 5fa0ed0..ea6b86b 160000 (submodule)
--- a/docs/submodules/dovetail
+++ b/docs/submodules/dovetail
@@ -1 +1 @@
-Subproject commit 5fa0ed07f830a6cd225689d9771e4cb480c4332a
+Subproject commit ea6b86b2d5aceea3dc54c3c4bf1d8a239fdde17d