Update git submodules

Update git submodules

* Update docs/submodules/releng from branch 'master'
  - xci: Create playbook to destroy, create and provision VM nodes

    This change moves preparation (cloning repos, combining opnfv/bifrost
    with openstack/bifrost), destroying and creating VM nodes from the
    script into a separate playbook.

    This requires the host to have ansible installed. The version of ansible
    to install using pip currently matches to what bifrost uses but it is
    hardcoded and needs to be fixed properly.

    The reason for having this as a playbook to simplify the script and
    increase the reuse. This playbook will be used for
    - developer sandbox
    - periodic bifrost jobs to run against latest on given branch and
    promoting bifrost sha1 to pin later on
    - daily jobs to run using pinned versions of bifrost

    Change-Id: I033f12290dfea19d4c74be80eea7203211c0369e
    Signed-off-by: Fatih Degirmenci <fatih.degirmenci@ericsson.com>