Update git submodules

Update git submodules

* Update docs/submodules/sdnvpn from branch 'stable/fraser'
  - create log file during logger initialization

    Currently the log messages from utils and openstack_utils
    python modules are not logged into bgpvpn.log. This is
    because this file is created during SDNVPN Feature
    initialization. So creating this file during logger
    initialization itself.

    Change-Id: I538acdfb2119f1eaa562f61dac3b6bf7c3a58e41
    Signed-off-by: Periyasamy Palanisamy <periyasamy.palanisamy@ericsson.com>
    (cherry picked from commit c1e5aafd5b5984b995d3ac6c74703e6a8be6e38b)