Update git submodules

* Update docs/submodules/apex from branch 'stable/euphrates'
  - Merge "re-enable support for fdio dvr scenario" into stable/euphrates
  - re-enable support for fdio dvr scenario

    - Update FDIO scenarios to use master branch images
    - Update VPP/HC version to master for all fdio scenarios

    apex-os-net-config: Ie6aee86eaccad5fc98820a28f10adc7475cc5e33
    apex-tripleo-heat-templates: Ie8b284f64bd6491c389129d8afdaeae8a399b607
    apex-puppet-tripleo: I9954240529278e74d93fdf89d2ebc2536249245a

    Change-Id: I31740f97052947b5e4688cca47320bc49a902d7c
    Signed-off-by: Feng Pan <fpan@redhat.com>
    (cherry picked from commit a3c2c8c746470c993d70d92d13415e2b4263cc25)

diff --git a/docs/submodules/apex b/docs/submodules/apex
index 5729ad1..c104a28 160000 (submodule)
--- a/docs/submodules/apex
+++ b/docs/submodules/apex
@@ -1 +1 @@
-Subproject commit 5729ad141664925d922ea6cbea7cdcde09d9b18c
+Subproject commit c104a284855069882e2625c57b5c2c78b0c6ba4d