Update git submodules

* Update docs/submodules/sdnvpn from branch 'master'
  - Replace heat client calls with openstack sdk

    JIRA: SDNVPN-220

    This patch replaces all calls of heat client with openstack sdk.

    Change-Id: I75571e8de8c06d144204af787ce240c99faea6d3
    Signed-off-by: Stamatis Katsaounis <mokats@intracom-telecom.com>

diff --git a/docs/submodules/sdnvpn b/docs/submodules/sdnvpn
index cfcb04c..90780e7 160000 (submodule)
--- a/docs/submodules/sdnvpn
+++ b/docs/submodules/sdnvpn
@@ -1 +1 @@
-Subproject commit cfcb04c938abdcddd76bcdd2375b4a81ea28fa51
+Subproject commit 90780e7d12b9003955cfbb8ff0155baf75b26323