Update git submodules

Update git submodules

* Update docs/submodules/snaps from branch 'master'
  - Merge "Return OpenStackVolume and OpenStackVolumeType instances from heat."
  - Return OpenStackVolume and OpenStackVolumeType instances from heat.

    Added a methods to OpenStackHeatStack to return any OpenStackVolume
    and OpenStackVolumeType objects it was responsible for spawning.
    Changes include all of the necessary changes to the heat and
    settings utilities and associated tests.

    JIRA: SNAPS-199, SNAPS-200

    Change-Id: I6da4bce1e90f080e22c96ab1b46eca8b85991ebf
    Signed-off-by: spisarski <s.pisarski@cablelabs.com>