Update git submodules

Update git submodules

* Update docs/submodules/sdnvpn from branch 'stable/gambia'
  - Using heat orchestrator for sdnvpn - test case 1

    Heat orchestrator and the use of Heat Orchestrator Templates
    is introduced in sdnvpn test cases. The deployment of the
    nodes and networks under test is performed as a stack with the
    use of the heat api and the use of the other apis is kept to
    as little as possible. The scenarios that are executed are the
    same as in the orginal test cases.

    This is the implementation of sdnvpn test case 1:
    VPN provides connectivity between subnets
    and also base functions for heat api access and some utilities.

    JIRA: SDNVPN-237
    JIRA: SDNVPN-219

    Change-Id: Ic284722e600652c9058da96d349dff9398bcacf1
    Signed-off-by: nikoskarandreas <nick@intracom-telecom.com>
    (cherry picked from commit cfcb04c938abdcddd76bcdd2375b4a81ea28fa51)