Update git submodules

* Update docs/submodules/sdnvpn from branch 'stable/gambia'
  - Fix error on querying neutron quota

    JIRA: SDNVPN-237
    JIRA: SDNVPN-233

    This patch fixes the bug which exists when trying to query neutron
    quota with openstacksdk.

    Change-Id: Iead824ca44f381ba314f38933cf48fe7932f74f3
    Signed-off-by: Stamatis Katsaounis <mokats@intracom-telecom.com>
    (cherry picked from commit edd6cfe15ecd4e2bf608c23c6ca4612334df044b)

  - Replace neutron client calls with openstack sdk

    JIRA: SDNVPN-237
    JIRA: SDNVPN-220

    This patch replaces almost all calls of neutron client with
    openstack sdk. The calls regarding bgpvpn are not replaced
    due to lack of support from openstack sdk at the moment.

    Change-Id: Idf52b8c57b895f87ba6320e350bf170faa24d0a7
    Signed-off-by: Stamatis Katsaounis <mokats@intracom-telecom.com>
    (cherry picked from commit ebf6885a907379083b360ae729f69151c1dd8115)

  - Updated from global requirements

    Change-Id: Ie87ea1677d0657a24ede0273f81313e33dab7df6
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/sdnvpn b/docs/submodules/sdnvpn
index 3dcc7e7..5f3157c 160000 (submodule)
--- a/docs/submodules/sdnvpn
+++ b/docs/submodules/sdnvpn
@@ -1 +1 @@
-Subproject commit 3dcc7e7801c39053e08bdc6c45402267d31ae56d
+Subproject commit 5f3157c897eaa5ef538d716e905f55085654a6c5