Update git submodules

Update git submodules

* Update docs/submodules/so.git from branch 'master'
  to 15b9f3c6cbb69a243e4fd98add2cc2aebe83daf4
  - Merge "serviceinstanceid being overwritten by vnfid in"
  - serviceinstanceid being overwritten by vnfid in

    Added check for vnfReplace before setting serviceInstanceId
    Added test to make sure serviceInstanceId is not overwritten
    Removed unused action import from WorkflowAction
    Formatted WorkflowActionTest to fix build failure

    Issue-ID: SO-2553
    Signed-off-by: Benjamin, Max (mb388a) <mb388a@att.com>
    Change-Id: I04cc668d4afbecd67b169f4e9d357ffc68cab02a