Update git submodules

Update git submodules

* Update docs/submodules/policy/engine.git from branch 'master'
  to 939cf950022f89aec547d3a6a9f6b9443b7a8a95
  - Improve ONAP-PDP-REST JUnit test case independency

    Handle cleanup of changed system properties and other test-related
    static parameters to prevent unexpected behaviour of other test cases
    that are dependent of the same properties and parameters when order
    of the execution changes

    Add Samsung modification copyrights for changed files

    Fix some loggings and a minor typo in documentation

    Change-Id: Ib6920d6300da79bfc426e4f348b503e3fd6a31ee
    Issue-ID: POLICY-1501
    Signed-off-by: kaihlavi <l.kaihlavirt@partner.samsung.com>