Update git submodules

Update git submodules

* Update docs/submodules/sdnvpn from branch 'stable/danube'
  - Fix security group rule conflict

    -open_icmp_ssh function, that creates security
     group rules for icmp and http (here the name of
     the function is misleading),  is splitted into 2
     new functions one for each rule (open_icmp() and
     open_http_port()).
     Test cases that used the old function have been
     updated

    -In the original implementation of open_icmp_ssh()
     and open_bgp_port(), the direction parameter was
     missing. This was leading to an error message

    -A check for the existence of security group rule
     has been added and used before the creation of each
     security group rule. If a rule already exists,
     an info message is printed and the testcase
     continues

    This change is strongly dependent on https://gerrit.opnfv.org/gerrit/#/c/31925
    of Functest repo. NOT TO BE MERGED before

    JIRA: SDNVPN-103

    Change-Id: Icb96954556f6d7294cf3454f045dbca4b9be672d
    Signed-off-by: tomsou <soth@intracom-telecom.com>
    (cherry picked from commit 0e26e7dfd4ff41ae7c8389218bca138346864922)