Update git submodules

Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - [salt.sh] Ignoring files using rsync

      Currently rsync is not ignoring '.gitignore' file due to the
      specification of absolute path. This patch fixes the issue and
      also ignores the temporary directory if that is created inside
      the cloned fuel repo

      PatchSet2: Shell check
      PatchSet3: Minor improvements
      PatchSet4: Rebasing the commit

    Change-Id: I05fc39236af1bc6f8eabb668304ba5a32dec0737
    Signed-off-by: Junaid Ali <junaidali.yahya@gmail.com>