Update git submodules

Update git submodules

* Update docs/submodules/sdnvpn from branch 'master'
  - Move import_modules inside try block

    Its still sdnvpn testsuite is failing at testcase_8 for bgpvpn ha
    scenario whereas it runs fine in the local setup. There is no logs
    generated from the CI run, moving import_modules inside try block
    and added few info logs to find out what is going on CI setup.
    [1] http://artifacts.opnfv.org/logs/functest/lf-pod1/2018-03-03_23-12-24/bgpvpn.log
    [2] https://build.opnfv.org/ci/job/functest-apex-baremetal-daily-master/827//console

    Change-Id: Icffa48cd56222bc1063ca16704e90a899380634d
    Signed-off-by: Periyasamy Palanisamy <periyasamy.palanisamy@ericsson.com>