Update git submodules

Update git submodules

* Update docs/submodules/vswitchperf from branch 'master'
  - Merge "python: Pylint 1.8.2 code conformity"
  - python: Pylint 1.8.2 code conformity

    Updated master Python scripts to conform to the newer pylint
    1.8.2 standard.

    JIRA: VSPERF-563

    Change-Id: I19305a008a2e22c2f4841aa83fed85fbdc2d549c
    Signed-off-by: Richard Elias <richardx.elias@intel.com>
    Reviewed-by: Martin Klozik <martinx.klozik@intel.com>
    Reviewed-by: Al Morton <acmorton@att.com>
    Reviewed-by: Christian Trautman <ctrautma@redhat.com>
    Reviewed-by: Sridhar Rao <sridhar.rao@spirent.com>