Update git submodules

Update git submodules

* Update docs/submodules/functest from branch 'stable/danube'
  - Merge "Check a rule existence for a specific security group" into stable/danube
  - Check a rule existence for a specific security group

        Implement a functionality to check if a rule concerning
        a specific security group exists
        - function get_security_group_rules(neutron_client, sg_id)
          returns the list of the security rules for a specific security group
        - function check_security_group_rules(neutron_client,
                                              sg_id, direction,
                                              protocol,
                                              port_min=None,
                                              port_max=None)
          checks if a specific rule for a specific security group exists
          and returns True or False
        - implement unit tests for the two new functions

         This new functionality is needed for sdnvpn project

    Change-Id: Ib930bc9a76141932f4164d88e2640b49f3df4d77
    Signed-off-by: tomsou <soth@intracom-telecom.com>
    (cherry picked from commit 41b103d9a6804a97ca85e2b09b628cea06219faf)