Update git submodules

Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - Revert: Blueprint "bp/distributed-serialization"

    Until upstream fixes bug [1], partially revert blueprint
    implementation [2]:
    - fuel-agent: no-op, we overwrite fuel_bootstrap_cli.yaml anyway;
    - fuel-library: no-op, keep newly added port config in place;
    - fuel-web: revert all blueprint related changes;

    NOTE: When this blueprint becomes part of Fuel@OPNFV, we need to
          update our "fuel_bootstrap_cli.yaml".

    [1] https://bugs.launchpad.net/fuel/+bug/1676197
    [2] https://review.openstack.org/#/q/topic:bp/
        distributed-serialization+status:merged+branch:stable/newton

    JIRA: FUEL-265

    Change-Id: Icf392a3446e5c89c2592d1733bc1f3401b7d69ad
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>