Update git submodules

Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - [baremetal] Switch VCP base image to UCA

    Since Mirantis prebuilt image comes with salt-minion 2016.3 instead
    of 2016.11 and upgrading it leads to a hard to break catch-22, use
    the Ubuntu cloud archive image we already download for FN VMs and
    pre-install:
    - a newer kernel (hwe-edge);
    - salt-minion (2016.11);
    This also implicitly aligns the image handling on AArch64 and x86_64.

    Change-Id: I86d1c777449d37bdd0348936a598e3ffe9d265af
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>