Update git submodules

Update git submodules

* Update docs/submodules/policy/parent.git from branch 'master'
  to 2f5f116faa66414da147618ba137e6efd394e166
  - Upgrade xstream to 1.4.11.1

    While analyzing drools-pdp, it's mvn clean install works
    fine with this fix locally.

    Also exists in engine repo, its mvn clean install works
    fine with this fix locally.

    distribution repo inherits from engine. also mvn clean install
    works fine with this fix locally.

    Issue-ID: POLICY-2001
    Change-Id: I25bd1f5d459f3ad279f1ce57fa0b153af21ece90
    Signed-off-by: Pamela Dragosh <pdragosh@research.att.com>