Update git submodules

Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - [lib.sh] Add veth pair handling support

    Upcoming docker integration requires special care for network
    interfaces Docker will hook to, so virsh networks can be mixed with
    Docker networks.
    We'll use veth pair(s) to hook together the Docker network(s) to their
    counterpart virsh-managed Linux bridge(s).

    JIRA: FUEL-383

    Change-Id: I1a714dc8be73e79539d85bacac311d1ed05cc18d
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>